I can calculate quite well and find some nice tactics when I'm refreshed, which is usually not the case, unfortunately.
My favourite living professional would have to be Vassily Ivanchuk. The humble way Vishy carries himself always wins my respect as well.
I will almost exclusively resign after I blunder anything more than a pawn. It's just respectful to my opponent. I don't want to imply that I don't believe they can beat me up an exchange. If I don't resign, maybe it was a sacrifice or perhaps there are some immediate chances.