@ White Elk:
Judging by the previous contests, I'd have to say no chance at all. For one of the polls Kael mentioned that the team had voted for an entry to be included in the final poll, but he had to axe it because it could not be implemented. So I am thinking that the deciding if it can be implemented or not is one of the
LAST things done before we get to vote on them.
FWIW, here is my opinion on your entries:
Chaos Orb (Cute text for the name BTW): I think it is possible overall for most of it, though it seemed a stretch at first, it is actually easy to do the majority. Replacing the Hawk would probably be done indirectly, making it a completely seperate unit instead of a modification of the Hawk itself (since many mechanics change). Grant the new unit recon and rebase abilities, and replace the Balseraph Hunter and other Hawk carriers with special units able to instead carry only Chaos Orbs. Allow an attack function similar to Fireball (destroys unit on attacK), but with the random effects you want (a modified mutation spell essentially). -- Only thing I would say is probably hard to code is the changing of visible terrain. I am not entirely sure if that one is possible, but there is a defined code entry for what is visible to the orb, and blight does do random terrain effect, so I think everything you need is in the game.
Ard-Luibh: Seems really easy. Though personally I think that all the wonders trying to make an alternate source of reagents are mildly annoying. So at least yours tosses some other things in there as well (if the map don't have reagents, adjust!

Not that I often make it to the point of seriously needing them anyhow)
Apprentice Jack of all Trades: Already talked about this one I think... meant to anyway. Only part I do not think is possible is to allow you to build a replacement Archmage should one of your initial 3 die (but getting the 4th in the first place is easy. Cap doesn't block a free unit, just the promotion "spell"). But if the new unit had the same stats as an archmage, but was a different unit, then it would work easily. It also might be difficult to track what spells they have cast as conditions for the quest. But it might be possible to base it off simply having a level 2 promotion from each of those spheres. Haven't seen a quest requiring specific promotions before though, so maybe not. :shrug:
@ Beorn:
Your event proposal makes a religious victory impossible

Since it would presumably take you more than 16 turns to get from 50% influence to the 80% required to get your victory, it is almost a guarantee that the event will trigger (Since you require at least 2 other civs follow the religion as well for victory IIRC. But at the least it is almost guaranteed that at least that many will follow it at 50% unless you are near a conquest victory).
If you cap it at once per game, or at least once per religion, then it still makes a religious victory twice as hard, but manageable.