It has been a while since I read C and P but IIRC he killed the moneylender in order to pay his rent and do good deeds with the rest of the money.
C and P is a much better read, in my opinion, than Lolita. It is multi-layered and remains amazingly readable and contemporary. (Although, I don't know how reliable the translation I read was, am not Russian scholar!)
I struggled through the second half of Lolita with its clever wordiness and convoluted use of language. I found C and P unputdownable and very structured.
Again am struggling to remember, but aren't there some interesting female characters in C and P plus exploration of prostitution/poverty and the patriarchal nature of marriage? Certainly the characterization is brilliant.
I think Nabokov wanted to push boundaries with his book and explore certain themes - he used the characterization of the sort of person who would rape a 12 year old to do this. I'm uncomfortable with that. I also agree that this book does not help women and it doesn't seem that that was in anyway Nabokov's intention.
He must have known that the subject matter was going to make the book controversial and notorious - that seems massively disrespectful to abuse victims.
If Dostoyevsky had used the murder of a child in order to write C and P, I doubt I would have liked it so much.
I haven't read either of these books since becoming educated about feminism - it would be interesting to re-read them using feminist analysis.