terraforming

I think on Mars, being suddenly fried would be an issue, but not that huge. Plasma shielding could quite easily be a permanent solution. But yes, looking for others would also be a good idea. I'll get back to you if I ever get anywhere in the field of plasma physics (:

Unfortunately, there is no chance of re-acclimatising a bone and muscle degenerated person. I do believe it is permanent. At least on the scale of 1/3 gravity would be.
If they went to Mars to stay on Mars, then no, it's not an issue. Returning will always be a factor unless we can find an artificial way of preventing, decelerating or correcting that level of degradation.
Of course, when I get home I should have a look into this.
arXiv.org is an excellent place to look up papers on anything, so if you feel like looking up anything at all (or anyone), there is a great place to start.
Please take anything I say on biological matters with a grain of salt, I only have first year university bio (I'm adv. physics major in third year), and I'll have to verify anything here.

Poke and prod me via PM if I don't get back to this