W.I.P = Work In Progress
Lots of Questions are here, I seek answers so we can share this information to everyone so people won't have such a hard time finding, making it or just choosing to give up on it! (Note that I do not know most of these things) It will be updated/changed as we gain this knowledge from others, Try spreading this post around.)
Answers must be as Informative/Detailed as possible, if you cannot do that, just write what you know and i'll handle it. Tutorials on Youtube will be made for all these things as well.

Q: How do you add a Teddy Bear Easter Egg that plays a Song when completed?
A: ?

Q: How do you add a functioning Jukebox?
A: ?

Q: How do we change songs in the Jukebox?
A: ?

Q: How do you make a Custom Perk?
A: ?

Q: How do we change the effects of a perk? make the effects stronger basically. (ex: Stamin-up lets you sprint twice/triple as fast as before or Jug lets you take 300% dmg before going down than the regular 200-250%.)
A: ?

Q: How do you make so Teddy Bears, Perk Bottles, or Other Chosen Thing (easter egg), opens a door instead of playing a song?
A: ?

Q: How do you make a Boss Zombie that spawns every now and then? (every 5/10 rounds)
A: ?

Q: How do you port weapons from another game (ex: black ops 1 or 2) into the map?
A: ?

Q: How do you remove dogs? (without it causing a problem when launching map)
A: ?

Q: How do you make a Custom Drop? (drop= max ammo, nuke etc.)
A: ?

Q: How do you add Custom Textures? (walls, floor, text etc.)
A: ?

More will come, Questions? Reply to this post and i'll add it if it's not here, an answer? Awesome! I'll add it asap to this list.