I have not looked at any posts after the post these questions were in, so I stole no answers.

1. What kind of weapon can turn horizontal springs around?
RF Missiles.
2. What item in the Psych tileset are you most likely to get stuck in?
The spikes. They go up and down, up and down, up and down.... AHHHH!!!!
3. What can you not do while confused by a smoke ring?
Run.
4. What two items are found behind some of the rocks in the Jungle levels? (Some rocks have none, some have the first item, some have the second.)
Silver and Gold coins.
5. If you shoot a tree that is in midair, what does it do?
Tilts over until it is at a ''--__ or __--'' angle, unless it hits something else first, in which case it stops there.
6. What non-custom level features a spring with a Generator?
Race1.j2l
7. What does a spring with a generator do?
Specify more. Horizontal ones, for example, fall down until they hit a solid tile, allowing horizontal springs and no fire zones to be in the same tile. (Think hotel jails)
8. Which level difficulty (Easy, Medium, or Hard) requires you to play an extra level if play single player from start to finish?
Easy. It makes you play Rabbit in Training, using a method that is apparently unable to be duplicated.
9. What tileset (if the answer was Moo then Moo 1, Moo, Moo Night, and Moo 2 would all be acceptable) is used by the only JJ2 single player level to contain a secret or bonus level?
Medivo, for Medieval Kineival.
10. What is the "third" list server that is contacted for some reason regardless of what you have in Regedit?
I hate techincal stuff. No idea.
11. What does shooting ice ammo at TNT do?
Depends. If the tnt is not picked up, it falls down. Otherwise, the tnt freezes, soon afterward exploding.
12. How do you make ceiling spikes?
Put an invisible enemy on the tile you wish to use. "Bees" is best, because it generates at lightning speed.
13. What enemies have two stages (for instance, you shoot one and it turns into another.) not including bosses?
Float Sucker, Float Lizard, XMas Float Lizard. Also Normal Turtle and XMas Normal Turtle if you count the turtle shell.
14. Which boss only has one frame of animation?
I presume you mean the Tweedle boss, though we can't be sure. One frame of animation visible.
15. What was Jazz Jackrabbit originally named and what was his occupation?
Wubbo Ockles, named after Arjan's dog, who was named after someone else I forgot. His occupation was a spaceman. (And his name was later changed to Jazz, after a coworker's dog)