On Concertos, I'd suggest starting with a one movement piece. Totentanz is very flashy and dark, but might be a bit too difficult (you might want to look at the score and see, it's on IMSLP). Also, a lot of Gershwin is fun, recognizable, and not too difficult. If you really want something 3-movement, Gershwin's Concerto in F is probably not too difficult. Mozart is always a good starting point, and some of the less dfficult Bach concertos. If you want to do a piece that is perhaps a bit too difficult for you, study some other, smaller works by that composer, as this might better help you understand their style. Oh, and please, please, please don't try the Rach 3. Don't end up as one of those "I just learned Fantasie Impromptu, I can handle anything!" people.
One last thing I forgot to mention, is that it might be worth your while to try some less main-stream concertos and see if you find anything new and exciting.