The photos seems to be gateways between timelines, and I imagine Max will use the one she took of Chloe and her father to fix things, let it all play out the way it should again. Incidentally, when I think about it, it's possible that Rachel and Max might be one and the same person; Perhaps explaining why they are never in the same place together, because they can't coexist, taking into account that Rachel is seemingly the polar opposite of what Max is.. and people keep mistaking Max for Rachel when wearing her clothes too, they oddly suit her quite well. It's just a thought best and not necessarily true at all but one can't help but wonder.
I don't think the new timeline would be permanent, if it did then it would deprive choice from you, undermining the whole theme of the game's story -- No, I believe that it serves as an ill omen of sorts, like the dream of a tornado by the lighthouse, to teach Max to teach Chloe that life could be worse and we make the best out of what we already have and move forward.
Chloe being in a wheelchair is most likely related to the whole 'cause and effect' concept, you prevent someone from dying and an equally terrible tragedy will take its place. Not so much time travel, as it is crossroads in the river, creating new leaks(new timelines) ala Stein's Gate or even like Mr Nobody in regards to the young boy's choice of whether going with his father or mother when they separate.