Actually, the corner bead shown can be bent back quite a bit easier than removing and replacing it. Find yourself a heavy chunk of straight steel, about 5 inches long and a half inch thick. Hold it against the bent corner, and with repeated small taps with a heavy hammer, you can return it to its former location. You'll have to re-nail it to the corner once it's straight, as some of the adjacent nails will have worked their way loose.
Texturing drywall mud takes some practice. For your situation, possibly a heavy, natural sponge used when just barely damp, and deliberately pushed into the mud after it's had a chance to take a partial set. I wouldn't try to do it all in one shot, but rather several coats (first heavy, then a lighter follow-up or two).