As I have said before, "Escort" is not the best term.
"Escorts" do not necessarily have to fly in the same formation, nor do the Chinooks have to fly at Vne even if they are capable for a given mission.
Transit is done above effective small arms range. The vulnerable periods are take-off/climb and descent/landing. "Escorts" can depart early to arrive at the LZ in advance of the lift hels, which gives time to recce the LZ prior to arrival of the big fat prime targets Chinooks. This is similar to how pathfinding was conducted in the Kiowa days.
As for crewing/maintaining, there is obviously going to be a training period required and pers will have to come from within the Tac Hel community so some accommodation will be necessary. How that will be done is mere speculation at this point.