So, in a couple of my maps I want to add a few things to them. Some of these items include: Fog, Custom skins for zombies and players, and non WaW weapons. How could I add these items to my maps? Also, is it possible to add a single boss, like the Panzer Soldat from Call of Duty Black Ops 2 Origins, or at least a reskinning the UGX bosses?

P.S.

I use the UGX Script Placer, if that makes any difference for how the coding for these items

I recommend following ZK's tutorials on how to make custom skins here: https://www.youtube.com/watch?v=aubHKZ-Hk2E

You can add bosses, but if you want to add the Panzer Soldat, good luck there. There are tutorials I know of in the zombiemodding user tutorials section where you can add boss zombies (zombies with different models/skins with more health).

If you want no WaW weapons you've got 3 options:
1. Port them yourself
2. Get them from somewhere or someone
3. Use the UGX mod

(If you're a new mapper and don't want to go through the hassle of porting or installing stuff then use the UGX mod, it's easy and gives you ALL non-WaW weapons)

In terms of fog I believe what you do (I'm only speculating here but hear me out) is that you create a brushmodel in radiant (or brush idk) of the texture "fog" and place it in areas that you need it in. OR you could use UGX easy fx if that's the kind of fog you're after: http://ugx-mods.com/wiki/index.php?title=Easy-FX

If you have any questions or want more information just ask or PM me! (I'm happy to help!)

- Ping

Pretty sure the radiant fog brush doesn't do anything.

Easiest way to do level wide fog is adding it via script rather than spawning fx.
This should help you out: http://ugx-mods.com/forum/index.php/topic,4697.msg52167.html#msg52167

Or there is another way to do it by adding a line of code in mapname.gsc. Both yield similar results. Hope this helps

Thank you to both of you for your help and suggestions, I'll be sure to keep in mind what you guys have typed