Unfortunatley none of these are questions I know the answer to! The closest I have got to this stuff is watching it being used on TV!

All the insulation spray I have ever used it wet and really sticky when it comes out. You could probably spray a little enough amount though.

I used it as an experiment on some "water bottle" chemical tanks, and I would say it will burst open any paper model, plus as others have said it's very "wet" when it first comes out.

"Great Stuff" ain't easy to cut.... so good luck with that and keep the vinegar and plasters handy!

If someone where to try and cut it to fit into the piece I would just try using Styrofoam. Its very easy to cut.

Ok well after giving it a go I think this stuff is awesome!
A couple of points worth noting:
- For the love of all that is holy wear gloves, this stuff sticks like you wouldn't believe and is harder to pick off skin than superglue!
- This stuff is not wet enough to warp 250gsm paper and I don't think it would be a problem for 110lb (about 200gsm)
- This stuff is a lot like shaving foam, it expands straight away rapidly (which is easy enough to factor) it then continues a slow expansion about another 50%... I didn't factor this in

I would say this is the perfect solution to vehicles and the like to make them a LOT more robust. It will take a bit of practice to get the quantities right.

For application, fully assemble model except for one face (for the car I did it on, I left the underside open, if possible with that last face glue one edge to make a hinge. Spray in the foam, try to get an even distribution, so long as the model doesn't have big faces (larger than 5cm x 10 cm, the faces won't bulge much with expansion and it will expand into corners without a lot of trouble. Now use the natural stickiness of the foam to seal the last face and hold it for at least 30 min (a vice is really useful here). then leave overnight, clear up any seep-age by cutting it away and you're done!

Interesting. Are you going to post some pics?