Has anyone heard anything about Blizzard secretly upping the spawn rates of vanilla-Azeroth rares?
Not to our knowledge, no, but I've noticed the same "Rares are everywhere!" thing myself. As other commenters have observed, this is the likely result of faster leveling and fewer people spending significant time in lower-level zones. Consequently, the odds of finding a rare spawn alive are pretty good, but this doesn't apply to rare spawns that people still have reason to care about, like Humar.
Assuming that the proportions on Wow Census are correct, there are some serious racial imbalances. For example, the data shows that humans make up 20% of all toons, which is five times that of Trolls (4%). Gnomes and Dwarfs have similar percentages...Do you think this is an area that Blizzard will have any concern about and if so how might they deal with it?
Beware, readers, for we enter the murky Land of Conjecture, from which we will not emerge for the space of several paragraphs.
If Warcraft Realms is accurate or at least in the ballpark, then yes, there are some fairly severe racial imbalances in the game, mostly in the form of Human, Night Elf, and Blood Elf "overpopulation." My sense of things is that Blizzard is ultimately concerned about racial imbalances insofar as they affect faction imbalance, e.g. it's not a big deal if lots of people want to play Humans rather than Trolls, but Alliance severely outnumbering Horde (or vice versa) is a sign that something's wrong.
Some of this is completely beyond Blizzard's control; they can't do anything about the fact that Elves, in whatever form they arrive, tend to be extremely popular in MMORPG's and fantasy games. Some of it, if previous statistics on the matter are accurate, is the result of World of Warcraft drawing a large crowd of nontraditional gamers who generally felt more comfortable playing Humans and Elves. Overall, most people just seem to prefer the aesthetics of the most recognizably humanoid races in the game.
But some of it -- this is just my personal opinion, so comments on this are welcome -- may have something to do with the fact that some race/sex combinations just have less sense of "polish" and fewer compelling animations to them overall, and this alienates potential players. Male Trolls, for example, have had a bizarre "creeping" texture issue with belts since beta. Female Tauren wearing chest + pants combination rather than a robe can't sit down without their tabards bugging out, and still appear with their eyes closed in the default unit frames. Female Orc and Troll braids fly straight through their shields (noticing a pattern yet with Horde females?). But this doesn't matter as long as their roles in a raid or group are covered by another character. Who cares if nobody rolls a female Troll Warrior when so many male Tauren Warriors are around?
Well, Blizzard does care -- they don't want to put stuff in the game that people don't want to play -- but cosmetic concerns run a distance second to game balance concerns, until the former starts affecting the latter. Perhaps the best example of this is what we call the Dwarf Priest problem. Pre-BC Dwarf Priests were the only race/class combination with the amazingly useful Fear Ward...but not that many people wanted to play a Dwarf in a dress. Alliance guilds drove themselves nuts trying to get them. Priest players complained about being forced to play a race they didn't necessarily want to play in order to get that one spell. Horde complained about not having access to what was inarguably the best Priest racial in the game (and then complained further when Blizzard relented in BC and gave Fear Ward to...Draenei? I'm still scratching my head over that one). Put simply, it was a problem created in no small part by a purely cosmetic concern; most players would rather play a Human or Night Elf Priest, and many wound up doing just that. Blizzard finally gave up after tinkering with the issue for the length of BC and gave Fear Ward to everyone.
Giving a free 80 of (underplayed race/class) to people obviously isn't in the cards, but I still think the lesson from the Fear Ward fiasco is valid; if a cosmetic issue (which is what drives race choice for most players) winds up exercising a negative influence on the game, you can expect Blizzard to attempt to correct the source of the imbalance, or at least to mitigate its effects. In the future I do hope they overhaul character models and some of the less compelling animations to make some of the underplayed races more appealing, but who knows when (or if) this will happen.
Before starting to tank heroic dungeons or raids, should future tanks (in this case a tauren warrior) be hit and/or expertise cap(ped)?
Sorano is actually someone with tanking experience from BC, but for anyone who's stepping into tanking for the first time, it needs to be stressed that your first priority as a tank is to get defense-capped; threat production is a moot point if you're just going to get annihilated by crits. For Ferals, this requires 3/3 Survival of the Fittest; for plate tanks, this requires 540 +defense for level 83 raid bosses and 535 for heroic bosses. If you haven't done this yet, then nothing else you do as a tank matters.
When we talk about expertise for tanks and the "cap," people are really talking about what are two different caps:
The "soft" cap is the one that DPS cares about: 26 expertise (214 rating), or the removal of a raid mob's 6.5% chance to dodge. Beyond this, a melee DPS located behind a mob (which is where melee should always always always ALWAYS be) gets absolutely nothing from expertise because mobs can't parry or block from behind.
The "hard" cap is the one that tanks care about: 56 expertise (460 rating), or the removal of a raid mob's 14% chance to parry your attacks. It's important to note here that, for a tank who's always in front of a mob, until the soft cap you're pushing both dodges and parries off the mob's avoidance table, but from 26 to 56 you're pushing nothing but parry off (and past 56, expertise is worthless). Dodges are annoying and negatively impact your threat-per-second, but parries are both annoying and dangerous due to the parry-haste mechanic, wherein a successful parry partially resets a mob's or player's swing timer. In other words, you get hit faster and more frequently, which is rarely a good thing for a tank (unless you're a Warrior or Bear Druid, outgear the encounter, and need rage).
If you're just entering heroics, expertise is great to have, and you shouldn't have too much difficulty getting close to or somewhat beyond the soft cap between talents, drops from normal dungeons, crafted, and reputation gear. That said, don't freak out if your expertise is lower than you'd like. Concentrate on getting to the soft cap, but if you're not quite there, don't let that keep you from tanking a heroic. Moreover, I don't believe that reaching the hard cap is currently possible for any tank outside of raid gear.
Hit's a somewhat different matter. Since Blizzard removed the base 1% miss chance for all players, the hit cap is 8% or 262 +hit for tanks (who are all assumed to be a 1H/shield or 2H weapon player; even Bear Druids are understood to be a 1H weapon mob. We will pass over in disapproving silence the specter of dual-wielding DK tanks). While +hit does nothing to affect your avoidance, it does, in a roundabout way, affect your mitigation, e.g. if you waste time trying to get something like Demoralizing Shout up, because your ability to apply these to mobs is affected by +hit, as are most taunt abilities. Aside from that, it is a TPS stat, and you are well-served by acquiring some. It is possible to get hit-capped outside of raid gear, but this probably won't happen for you until after you've already tanked a number of heroics and gotten some badge gear.
The good news is that tank threat is not designed around tanks being able to hit the mob with each blow, but you're more likely to feel the pinch from low +hit or +expertise gear if you're tanking for people who outgear you. If you're really hard up, you can always fudge your stats a bit with Rhinolicious Wyrmsteak (for +expertise) or Snapper Extreme (for +hit).
So, TL:DR -- do you need to be expertise-capped? No, but reaching the soft cap should be pretty easy with a little effort, and may happen as a matter of course while you're on your way to the defense cap. Do you need to be hit-capped? As with +expertise, you're likely to acquire a nice amount of +hit on the gear you need to tank anyway, but keep an eye on your TPS in heroics. If your DPS are playing responsibly and still getting threat-capped, then you need to adjust your rotation, start prioritizing more +hit, or both.
Where is the best place for a new 80 BM hunter to start raiding?
Generally, it's a bad idea to jump straight into raids as a fresh 80 unless you've got a forgiving bunch of guildies prepared to carry you. Level 80 5-mans (Oculus, UP, HoS, HoL) or heroics are a better option. Don't be that guy!