You cannot create markers via scripts, but you can reposition an existing marker. Or, there are ways to detect when a user creates a marker on the map by double-clicking, which pre-date resistance.
As for the fastroping, I'm guessing that the script makes the guys jump out of the helo AS SOON as you execute the script. In that case, you would need to wait until the helo completes it's waypoint, and then do the rapel. I'm busy ATM, so I can't help you, but if you check the ed depot, there is a collection of helo scripts by Kammak that might work for what you are doing.