There are no real big changes between 2015 and 2016 BUT there are some things that all Challengers will need to watch out for and/or take advantage of. The source of this information is from the WoWHead.com Lunar Festival Guide.
Honouring Elders: You can absolutely go and honour Elders and take advantage of the free Experience Points they’ll give you. Honouring an Elder will give you a Lucky Red Envelope and a Coin of Ancestry.
Lunar Fortune Buff: In each of the envelopes you will receive either a Lucky Rocket Cluster or Elder’s Moonstone. Setting off the Lucky Rocket Cluster from a cluster launcher will give you the Lunar Fortune buff… this gives you +250 health and is NOT ALLOWED.
Quests: All quests are allowed, even the quest that requires you to defeat Omen, although I’m not quite sure I’d recommend trying it… if you die, that’s it.
Coin of Ancestry Redemption: You can turn in your Coins of Ancestry for pets, toys, food, fireworks and clothes.
Festival Dumplings: Allowed. Good health/mana regeneration. Stock up on these.
Festival Dresses and Suits: Allowed. They are all White-Quality equippable gear.
Schematics & Patterns: Allowed for Pacifists only. You can buy these from Fariel Starsong to craft cluster & firework launchers as well as festival dresses and suits.