Dear Faulty: There's nothing wrong about a Bbm following a Ab7. Never heard about deceptive cadence? Furthermore, it's usual in sonata form movements a big step backwards doing the repetion of part A. When you have a minor mode movement, the most common is to end the exposition in the relative (what is the case in this sonata: Ab7 is the dominant of Db). However, it's nothing wrong too about repeating from the beggining, or ignoring the repetition. If you have a repeat sign at m. 1 or at m.5 is up to the original source (Chopin manuscript) and, given this enlightment, it could not be considered the other way. But about doing or not the repeat sign is upon the performer. Best wishes!
Pianowolfi, I wouldn't trust Jan Ekier, he's very old and famous for being weird, plus look at what he did in Chopin's E-Minor Concerto. Do you like the C-Sharps instead of Cs? It's not in the autograph either...