Well, in novel he helped her to bypass her technique bottleneck, but never did her, cuz never believed her to be chaste.
As for harem, if I remember correctly second was pinkhead(Bai Ran), then mortal milf(from mu manor. for a long time they hadn't go past bj and hj so doesn't count), after...
Not really, for some reason author just skipped whole 12ch prologue part of novel. There s(he) "experimented" with new body(for almost full first day) and powers. And that stuff really needed to be explained:
MC power not just that of 98lvl Susie, but combined strength of all his many characters...