Dirtman,
Nam Pack 2 will overwrite Pack 1, using the same classnames for existing units. It will probably be for OFP:R due to things like pistols being included on units (but i might try to make it work in normal OFP as well). So to answer your question, yes your missions will still work if you have OFP:R.
I was going to try to keep this as a surprise for the release but all the door comments forced my hand! The cargo doors on the gunship will be animated, ie you can open and close them. You can only do this on the ground and if you land you have to get out to move them (that's the way OFP works, nothing I can do about it).
"Maybe release them in a special pack so everybody can choose if he wants to load it down."
The idea behind the Pack is that everyone has the same addons, making it easier for mission makers and MP servers. Releasing seperate sub-packs defeats this purpose.
SelectThis