Louise Candlish Yes, Ralph is feeling reflective (well, as much as he is able to) at the end and feels he wants to 'give something back'. The implication is that he and Leisha will soon see each other again when she moves into number 1 with her tricky new boyfriend. Will their odd little connection break down or will they get closer? Maybe work together or even have an affair?
Alex D I feel as thought at the end of the book all the characters including Ralph had begun to realise the world outside of their own echo chamber or rather the community outside of their street, and the importance of treating people with respect regardless of their background. Ralph was thinking how he could make a difference in the community and remembered the altercation with the girl and rather than thinking her less than him, he saw an opportunity to make a difference, in my opinion this thread was in place to show Ralph's character arc. Coincidence they also stand to inherit number 1?
Jules This is another good question. I think this seems to be a bit of a random connection that has not been explored fully by the author. Leisha does appear at the very end of the book and I think that the author 'suggests' that she is the partner of Darren's relative (meaning that the circle of destruction would probably and 'naturally' continue in the estate in some way presuming they would inherit the property and live in it) - it just seems like another clashing relationship. Although the author hints at this, I have also questioned Ralph taking an interest to Leisha and talking to her amongst her unfriendly peer group. It feels like an awkward thread to read - I'm definitely not sure what the author was 'suggesting' here. It seems like an awkward connection that is carelessly explored and out of place.
This answer contains spoilers… (view spoiler)[I don't think Ralph knew the girl had any connection to Darren. I think he sometimes wonders what his life would have been like if he hadn't become a success, how different everything could be- so when he travels to his old neighbourhood he's getting back in touch with his past in a way that is sometimes smug (as in 'look at all I've achieved') but sometimes curious and reflective (as in 'what if I hadn't become successful, where would I be now') I think he only sees Leesha as the young and poor single mom he almost hit with his car and he's making her a legitimate offer at a job- perhaps wanting to be the difference in someone else's life both in a truly helpful manner and in a more objective 'what if' sociological experiment manner. (hide spoiler)]
Vicky The girl from the estate was the one who was walking in front of Ralph's car earlier in the book (she shouted and swore at him when he asked her to move out of the road). It wasn't clear why he went to find her though, and how coincidental was it that when he went to find her she just happened to be standing right where he pulled over?