These are answered in order:
Yes, I have Played it before.
I really don't think so, but if you make an entity disapear (fake wall) and them make a script so that when the entity is destroyed, the cheracter goes to it. this is very complicated and glitchy.
See my valve portal thread, if it still exists.
No, unless you animate them with a holster animation.
You can use custom scripts to play a sound, or use sound zones as well. = Yes I am too busy to do this, though. Sorry.
No. Lightmaps have nothing to do with the FPI scripts. If you use trigger zones, an enemy could spawn in a zone when a player setps into the light. i.e. put trigger zones in areas with light. Tis way, there aren't a lot of enemies if the player stays in the shadows.
Best of Luck.
The Cake is a Lie!