1) I am pretty sure it is impossible to actually spawn a "live" satchel charge from the editor but what you can do is make the unit in question place the satchel once the mission starts.
you can do this by placing a waypoint (on the spot where you want the satchel) and in the on activation field place:
to make the unit set off the satchel place another waypoint from where you want the unit to set the satchel off and put this in the activation field:
Unitname fire "pipebombmuzzle"
If you want the player to do this and make him start with the active satchels you can try to first make the ai unit place the satchels and then switch the player over from another unit.
Unitname action ["TOUCHOFF", Unitname]
2) I am also pretty sure there is no way you can delete actions that are present by default (vehicle actions etc)
what you can do is make a trigger with as a condition the in vehicle commandhttp://community.bistudio.com/wiki/in_vehicle with a ! to check if the player is not in the vehicle
something like this :
And the in the on activation line something like:
This should have the effect that every time you try to jump out of the heli you get automaticaly put back in.
player moveInCargo heli