Maybe not exactly what you’re looking for, but if you know of a program that already does the thing you want, you can search for a variety of alternatives on alternativeto.net. It lists paid and FOSS alternatives.
No, Beehaw defederated your instance. The open-source community on lemmy.ml someone else already mentioned is your best bet.
Dunno. My account isn’t on either instance. If beehaw is federated with your instance, you would be able to post.