Random size/rotation/displacement

I am fairly new to UDK.
Currently, I’m designing the map:

As you can see I have a lot of trees and so on.
Is it possible to select them all and do a random rotate, random resize, random displacement (where it is x/z)? Preferably with constraints. (e.g. rotate 0 to 360, resize -10% to 10%, move -10z to 10z)

Extra questions:
When I place two unedited terrain right next to eachother, I can perfectly walk from one to the other. However, when I spawn a scorpion and try to drive onto the second terrain, it glitches. Why? and how to fix that?
Can I put a hole in my terrain? e.g. a trapdoor, and I go down below the terrain?

Thank you in advance.

Use the foliage editor to place your objects, and you can specify random size and orientation there. Not quite sure about your other question, I’d need more info regarding exactly what you’re doing.