I hope you get some response to this. I have been out of Orbiter for a year or so (the Crash, unemployment, starting my own business, fending off poverty, blah, blah, blah...). I just started this week poking around with Orbiter 2010, surveying the wreckage of my addons, seeing what works and what can be done to make things work.
I think the big problem is Multistage2 and Spacecraft3. They just aren't fully compatible with Orbiter 2010. I find that the Left Shift + Numpad key combinations (for animations) don't work unless I have the NumLock off. I suppose that could be either Orbiter 2010 or Windows 7 which I just got. What's your experience?
NASSP Apollo is also a bit of a golden oldie. I don't know if anything has been done to update it.
I will try to get Skylab addons installed over the next week or so and see what's what.