In my opinion, the questions you've posted are all on-topic here.
There is a site for pets, and aquarium keeping is part of that site. But they don't do identification questions, and while I don't think questions about propagating plants would be closed if they were asked there, I think this site would be the better place to ask.
If you're interested in getting more exposure, possibly reaching aquarists who might not normally visit gardening.se, feel free to post a link to your question in the chatroom of pets.se.
I think that if your question was more along the lines of wondering if letting the plant flower would be detrimental to the animals in the tank, then it would be better served at pets.se.