Need help with ambush mission

Currently making an ambush mission on the map of Tanoa, however Im having a few issues

1. The vehicle AI simply does not seem to work. They randomly go off course, stop moving, just fuck off into a random direction. Ive got it set up right now so that the vehicle drivers and crew are in a group with move orders in a column formation
2. When the ambush occurs I would like to make it so that the transport vehicle fully onload (drivers included) but have the armed escorts only transport unload

any advice on fixing my mission?