right, if you're talking about simple soldier respawning (not vehicles) for multiplayer, what u wanna do is create two markers (preferably oval or rectangular in shape) and name them respawn_east and respawn_west.
Place em where u want the respawn points to be for the respective team, then create a text file called description.ext in your mission directory, and inside it put
respawn = "Base"
respawndelay = 3
u can change respawndelay to however much u want it to delay before respawn.
By the way. This only works in TRUE multiplayer mode, so it wont work if u test the mission in the mission editor.
If you're talking about vehicle respawn, tell me and i'll try to explain
About the building thing... If u place a gamelogic over the building you want attacked, and then do 'this dotarget gamelogic' on the tank u want to attack it, then 'this dofire gamelogic', it should attack the building (well, really it attacks the gamelogic, but as its nr / inside the building it should work...)
hope that helps