I tried placing vehicles but npc_vehicle only spawns an untextured swoop. How do I place vehicles in the map?

you want to set the vehicle type.
select the vehicle entity (its the red box) , hit N,and look at the key and value settings. you need to change these to get different vehicles for example..... a SP swoop would be:

key: npc_type
value: swoop

..although i believe this is the default one, and thats what appears in the map. Now, you dont want an SP swoop in MP do you? so...

key: npc_type
value: swoop_mp or swoop_mp2 (ones blue, other is red)

another example.

key: npc_type
value: tauntaun

e.t.c.

Ok that makes sense, thanks