
As far as the alts go, I don't really see a problem. People come and go in our lives all the time in real life. It's relatively rare for someone to appear in our lives and then stick around for an extended time after that. For the most part, we'll meet someone (some random person you talk to at the coffee shop; the UPS delivery guy; the girl at the sports bar sitting next to you while you're watching the game; etc), interact with them, and then move on. With rapidly changing alts, it's the same thing. People might wonder "Whatever happened to Bob...?", but they'll move on if you stop playing the alt.
What to do about your main changing is a little different, of course. It's tough to show up one day and say "Hi, I'm an Au Ra, now!", and have an explanation for that. A lot of people don't consider fantasia to be canon, ICly, so it's problematic to just use that as an excuse. Personally, if I were you I'd just RP with my main and then, when I switched to Au Ra, I'd have my main be a different person. I'd explain OOCly to my friends what was going on, then come up with some little handwavey thing to close out my old main's story: Bob got rich doing whatever it was he did down there in Copperbell, and he retired to a nice little ranch house in Thanalan. This is Joe the Au Ra, he just arrived in town...
What to do about your main changing is a little different, of course. It's tough to show up one day and say "Hi, I'm an Au Ra, now!", and have an explanation for that. A lot of people don't consider fantasia to be canon, ICly, so it's problematic to just use that as an excuse. Personally, if I were you I'd just RP with my main and then, when I switched to Au Ra, I'd have my main be a different person. I'd explain OOCly to my friends what was going on, then come up with some little handwavey thing to close out my old main's story: Bob got rich doing whatever it was he did down there in Copperbell, and he retired to a nice little ranch house in Thanalan. This is Joe the Au Ra, he just arrived in town...