I'm going to get this out of the way right off the bat since I know I'll get a dozen people asking again this week: Yes, Know Your Lore will be coming back, it is not gone forever. I promise. I will pinkie swear on it, even. Come on, who wants to pinkie swear? Anybody? Anybody?
"On the topic of the Nerubians and the Qiraji, is there any relation in the lore between the two? Or are two insect civilizations coincidental?"
There's absolutely a relation between the two. They hold a common ancestry. Both the Qiraji and the Nerubians are offshoots of an even more ancient race, the Aqir. Way back when Azeroth was still very primal, and Trolls were the top dogs. There were three major players in the world: The Amani Trolls, the Gurubashi Trolls, and the Aqir. They warred for thousands of years. Thousands. It was a war of attrition on the grandest scale possible, and all involved more or less broke under the weight of their losses.
The Aqir Empire was split in two, between the North and the South. The Aqir in the north founded Azjol-Nerub. The south founded Ahn'Qiraj. After thousands and thousands of years, they just evolved differently, likely to adapt to their two very different environments. The Aqir basically ceased to be, and in its place were the Qiraji and the Nerubians.
"Is it my imagination, or are the Dwarves the only playable race that doesn't seem to be terribly screwed up by something in the recent past? The Orcs are atoning for decades of evil, the Humans, Undead, and Night Elves have deep psychic scars from the Third War, and the Gnomes, Tauren, Trolls and Draenei have all been forced to flee from their home lands due to invasion (those are simplifications, obviously). But what do the Dwarves have? They probably saw heavy losses in the third war, but no where near as bad as the Humans did. They have the Dark Iron Dwarves to contend with, but that doesn't seem to be too bad. Unless I'm missing something major, the Dwarves seem to be surprisingly stable."
The Dwarves have many words that describe them. Stable is not one of them. The Ironforge Dwarves have had just as much trouble as every other race on Azeroth, the only difference is that right now, they're in a relatively calm period compared to the others. Relatively calm does not mean calm, mind.
The War of the Three Hammers isn't terribly recent, but it set the stage for the current state of the Dwarves, for the most part. This War was a civil war among the Dwarves, sparked by the death of the former king of Ironforge, Modimus Anvilmar. The Bronzebeard Dwarves, the Wildhammer Dwarves, and the Dark Iron Dwarves were all once under the same roof, and the same banner. Modimus Anvilmar kept them all in line, more or less. Ironforge is currently one third the kingdom it used to be, with the loss of the Dark Irons and the Wildhammer. You can read up on that whole thing in our Know Your Lore article on Grim Batol.
More recently, the Dwarves lost a significant amount of territory in Khaz Modan to the Dragonmaw Orcs during the Second War. The Dragonmaw still have a pretty strong presence, as you see in the Wetlands.
Ironforge currently does not have an heir. Wait, let me correct myself: Ironforge's current heir is a pawn of the Dark Iron Dwarves, and has by now given birth to a halfblood that can technically claim the throne one day, unless Magni utterly disowns his own daughter and Ironforge decides not to recognize her hereditary right to rule. If they do that, then there really is no heir to the throne. When Magni passes, the crown is up for grabs, and it won't be pretty.
The other Bronzebeard brothers were completely missing until very recently, and the Explorers' League keeps sticking its nose where it doesn't belong, unearthing horrors never meant to be seen by mortal men.
The Dwarves aren't in a good spot. Not nearly as good as people make them out to be, anyway. All it would take is Magni choking to death on his ale to throw the place into chaos... unless the Dwarven senate can keep things under control, and I think we know the fantasy genre by now. The senate can never keep things under control.
Oni Stardust asked...
"There's something that's always bothered me about the Horde. Why is it that when the Trolls joined the Horde they were expected to give up cannibalism (and voodoo), but the Undead eat the bodies of intelligent creatures all the time and as far as I know Thrall hasn't said a word about it."
The greater Horde body turns a blind eye to a lot of things that the Forsaken do, really. The Forsaken probably get away with a lot of what they do simply by keeping themselves a safe distance apart from their allies. Thrall is either completely unaware of what the Forsaken do, or he's a hypocritical bastard for letting them do it. It's either ignorance or incompetence, it can't really go any other way there.
"What's the story around Path of the Titans, the ruined road that goes from Ulduar to the shore of Dragonblight? What bugged me is that it doesn't end on the shore of Dragonblight, it continues further and we see some ruins deep into the sea. On top of that, in Strand of the Ancients, which is supposed to be located in some island south of Dragonblight, you can see the road pass through the island and continue further south."
I can't remember where I read it/heard it, so please take this with a grain of salt: From what I understand, the Path of the Titans was a pathway that went from the top of the world (Storm Peaks/Ulduar), all the way to the bottom. It cut straight down the middle of Azeroth. It was built when the world was all one continent, before the Sundering. After the Sundering, the continents were broken apart and the Path of the Titans broke with it. Northrend is the only place we've visited where you would still see parts of it preserved. When we visit the Maelstrom, we may see some remnants of it there, too.