I think Ali would come to know Ryan through association. He and Alexa are pretty close and he'll be wanting to keep an eye on her as they settle in. I daresay he'd be spending a bit of time in Chopp over the coming weeks, so it wouldn't be a stretch for him and Ryan to bump into one another!
That's completely okay. There are always going to be people that don't get along and it makes sense that he and Eli won't mesh well.
I feel as though Mr Sawyer will fast become one of Ali's favourite people. He isn't the sort to spend too much time in the library but I think he and Tom would be able to strike up conversations and have a good time regardless! :)