Yes, Neville could have been the chosen one as well, but as soon as Voldemort attacked Harry he made Harry the only possible chosen one. So, if Lily had chosen Snape, they had had a child at the same time that Lily had Harry originally, and Snape and Lily still defied Voldemort three times, it's likely that Harry still would have been chosen.

I read at the Lexicon something about how Brian was part of Dumbledore's name as a kind of joke against the old fashioness of all the rest of his names.