Medics should exhaust to remove X damage from the attackers results before wounds are applied to the attached unit, with X being the level of the Medic keyword.
Mechanics should exausht to heal X wounds from a damaged vehicle at range 0-2, with X being the level of the Mechanic keyword.
Engineers should exhast to plant a mine token in base contact with the engineer figure, and should "arm" once the unit leader of the engineer's unit has exited range 2 of the mine. The mine should explode when an enemy figure enters range 2 of the token. The engineer should also have the cumbersome keyword.
(The job of a combat engineer is to make sure your guys don't explode and the other guys do.)