Walls:
Your 'wall' should be a func_door. Have its angles set to UP and it will move up. Give your func_door a name and make a func_button that targets it.

Gravity:
Gravity is hell. But if you want you can try to use a trigger_gravity or two. When you step into a trigger_gravity, your personal gravity is set from then on, even if you exit the trigger_gravity. You should be able to control a trigger_gravity with a multisource (i.e. turn it on and off). If you use a trigger_gravity to set someone's gravity to moon gravity, you'll need another one to reset their gravity back to normal.

Weaponstrip:
My solution to this was to name the weaponstrip and target it with a multi_manager. The multimanager was multithreaded and named game_playerspawn.

Anything named game_playerspawn will get triggered by players when they spawn. Multithreaded multimanagers only act on the player who triggered them, not the whole server.

?

multi_managers are different from all other entities.

They are sort of a hack. An awesome hack :P

To use it, unclick SmartEdit and add your own key/value pairs.

Think of each Key/Value pair as a TargetName/Delay pair:

TargetName is the the name of whatever you want to trigger.
Delay is how many seconds after the multimanager is triggered that the TargetName should be triggered.
Do not use 0 for the delay. Use at least 0.001 or strange problems can occur with many entities.
You can have up to 16 events triggered from 1 multi_manager at all different times.