1. I think 700 with everything is fine, especially since the RNG has been removed and you know what you will get. You're getting two paratrooper squads and the ATG you might as well consider a bonus.
This ability has some issues that make unattractive:
"Airdrop combat group" comes at CP 7 which more than double CP of most elite call in (almost 4 times in some cases), by that time a player probably has on the field as many infantry as he needs and even he just lost some squads and want to replace them he probably need 1 not 2 and ATG.
Further more since they already come with AT weapons the ATG is more of liability than a bonus since it can be used by enemy if the ability is used in the front-line or has to be crewed by the airborne with a higher cost.
In any case Coh2 offers a discount when someone buys units in bulk (ok free weapons can be considered a discount) but since the normal "airborne" come at CP 3 and cost 340 (680 for 2) this ability still is not very attractive.
6. Also on team weapons. No on increasing cost as these models have some of the worst weapons in the game and are as easy to hit as regular troops.
Yes but there are extremely cheap to reinforce a maxim or Dshk model is 15 mp to reinforce compare to a conscript with 20 (33% more cost)...
This change will promote support weapon spam since it will very cost efficient to reinforce such an army...
I have a series of other suggestion that you might want to consider and if you are interested I can post them here...