In the init field:
this setUnitPos "UP"; this setBehaviour "COMBAT"; this switchMove "CROUCH";
I do not think any of that is case-sensitive, I just am in a habit of putting those things in all caps.
The guy may stand back up if he wants to turn quickly or wants to throw a grenade.
This may be the #1 asked question on this board, but I do not mind, just do not ask twice. ;D