I really like the Young Wizards series! But I haven’t read it in years actually. The last one I read was Wizards at War, I think? I know there are only a few after that, but I never got around to reading them, haha. I always really liked High Wizardry, though Wizards at War was also super good. I like stories that go to space, obviously. My favourite characters were always the two (gay?) dudes who were Nita and Kit’s wizard mentor types, though I also liked the villain tbh. The two scenes that stick out most to me are the one in High Wizardry where Dariene is playing god on a distant plant and the one in Wizards at War where Nita is fighting everyone in the space airport.
I don’t know if they’ve influenced my own writing, honestly? Maybe? I’d assume that everything I read influences my writing, so probably, haha. As for the last part of your question, I was never involved in the fandom online, so I don’t have any recommendations, sorry!