as for the problem with making all the troops get out when you do, try typing this in the "on activation" field of your choppers land waypoint
'this land "getout"'. maybe you did this alredy, i dont't know. As for making it land where you want put in "empty/objects/h (invisible)". The choppers in the game are programmed to land on h's and with an invisible one, it works the same, with out having an H in the middle of nowhere. For the troops you can try putting "unassign vehicle group this" in the on activation field of the troops' waypoint, but it may make them drop out too high (and I might have my syntax wrong).