I avoid creator tumblrs (and related posting) because I like to go into games blind; also, sad to say, many games make it to the "Here's all the info, look forward to it! <3" stage before they run out of steam. As such, take whatever I say next with a grain of salt, since I've been avoiding even the tiniest spoilers! (So, no opinion on the names thing.)
* I'm good with canon genders, especially as someone who (sometimes, sort of) writes; sometimes characters spring into your head a certain way or evolve into a specific state, and it becomes hard to think of them otherwise. While I appreciate the option to choose RO genders, it's not necessary for me to appreciate and/or romance the characters.
* I'm not personally interested in poly relationships, though I know that some people prefer them or would like them to be available. It wouldn't turn me off unless it restricted characters to poly-only relationships, ex. I can't romance Character A unless I also romance Character B. It wouldn't be enough to make me swear off the game, but I might be a little disappointed if I wanted to start a (non-poly) relationship with a potential RO and couldn't.
I don't know much coding, so I can't give much of an opinion on the coding-based questions. From following the development of other games, though, it seems like trying to be too ambitious can be a one-way ticket to burnout, so don't feel like you have to meet all the expectations, especially not all at once. As a (future) player, I feel secure in saying that we're all supporting you, even if all we can do is exercise some patience!