[dllthomas]

Wouldn't another approach to (2) be eliminating debris and having satellites steer around it? We don't move buildings to dodge cars.

This isn't to say that's easy, just that there's more than one currently intractable way we might eventually be able to skin that particular cat.

Edited to add:

With respect to (3), there's apparently this: http://en.wikipedia.org/wiki/Van_Allen_radiation_belt#Propos...

I don't know near enough about it to say whether it's any sort of a good idea, but it doesn't seem hard relative to building a space elevator.