1. Is it possible to have a car with two people in it drive through a game_player_equip equipping them with a weapon and then disabling the game_player_equip so nobody else can use it?
I'd do it like this (not sure if this will work but I think it should. Also this is probably not the simplest setup but it's the first one that comes to mind.):
- make the car
- make a brush where you want the car to have to drive through, texture it with AAATRIGGER. Tie it to trigger_multiple. In its properties set the target to 'multi' and master to 'master'.
- make a multi_manager and set targets to 'relay' and 'equip'. Give it the name 'multi'.
- make a trigger_relay, name it 'relay'. Set its target to 'master' and trigger state to off.
- make a multisource and name it 'master'.
- make a game_player_equip, name it 'equip'. Set whatever weapons you want the players to get.
- make one of the spawn points high in the air and under it make a trigger_multiple. Set 'on' as its target.
- make another trigger_relay, name it 'on', set the trigger state to on and make it target 'master'.
Wow, that was even longer than I thought it would be. But I think it should work.
2. Can you make doors that are breakable, e.g create 10 doors that can open at the press of a button or if a door has 500 dmg done to it it will break open that way. Or would it be easier to make all the doors func_breakable and just have a button destroy them?
I don't think you can do that (maybe if you have both func_breakable and func_door and you trigger both at once in any case and make the one you don't want to be seen invisible with env_render but I'm not sure if this will work or not, I've never used env_render).
3. How can you make it so that once a player passes through an area, everyone else in a specific area is killed after 10 seconds.
Make the trigger area a trigger_multiple and make it target 'hurt'. Set the delay before trigger to 10.
Make the allplayersherearekilled area a trigger_hurt, name it 'hurt'. Set the damage to 100 (or more). In flags check Start Off.
4. How can you create custom entities for use by a mod/plugin.
Do you kow C++?
...and that's the bottom line because Mate de Vita said so.