You don't have to be level 70 to get in on most of the fun for this year's Midsummer Fire Festival. Here is a guide to the minimum levels required (as stated by Kisirani) and recommended for each of the quests:
- Torch Tossing and Torch Catching have no minimum level requirement. Because you complete these quests in the safety of a capital city, any level is appropriate.
- Honoring the flames has no minimum level requirement. Unless you are 50+, however, the recommended level is the same as the level of the area you can comfortably hunt in.
- Desecrating flames also has no minimum level requirement, but considering it flags you for PvP even on a PvE server, do so at your own risk if you are low level.
- Incense for the Festival Scorchlings also has no minimum level and any level is recommended.
- Unusual Activitiy requires level 16, but I wouldn't recommend lower than 20 given that you have to fight level 20 and 21 cultists and the area is rotten with level 20 Naga.
- A Thief's Reward or stealing the flames in the other faction's capital cities required a minimum level of 50, but if the flame is at all defended, it's best to be level 70.
- Lord Ahune requires a minimum level of 65. Slave Pens is where he resides,
so any level above the minimum that you feel comfortable in that instance is recommended.Edited to add: Upon further review, the recommended level to complete this quest is 70 and it is easier if the 70s in your group are well-geared.