Hi, Steve-O. I think it depends on the kind of wallboard that you have and the kind of adhesive you use for the paper. If you have vinyl coated wallboard and are going to use pre-glued paper, I am sure that you will have problems. Adhesives are available that will work but application to the paper will be A LOT more work.
I'm not sure about filling the joints but since you should be talking to your friendly local paint and wallpaper store about the adhesive, you should talk to them about this also. There are so many variations possible that definate information without knowing the kinds of products you are considering is impossible.
You should have no problem with outside corner if everything else is OK. You may want to consider clear plastic corner strips if you are at a location that will see a lot of traffic. Just fold the paper over the corner. Cutting at the corner is probably a better way but matching can get real hairy.