Hi Dani -- Sounds like a wonderful use of Photosynth, and you're very wise to be doing as much planning as possible before your airtime.
Max resolution? Full frame DSL (16-20 megapixels) will work great. We hit some limits above that at the moment, but will be working to get around them.
Manipulating the positions of the images isn't possible right now, but I don't think you're going to have a problem. Photosynth handles snow very well (as long as its not badly over-exposed)
We can't give out our standalone Photosynth builds unfortuantely. They aren't properly tested and could well give you as much trouble as they'd save you. On the other hand, with careful preparation, I'm SURE you can get a standout synth. I'm going to post a longer response with detailed instructions about synthing mountains from the air. I've tried it! Will post again tomorrow.
Best wishes, David.