itch.io

Usually, yes.  If you're not sure you can always post the source and someone here can try to give you a more concrete answer.  There are a lot of free and low-cost music sources you can use... esp. for a game jam.

yes, you can use an old template 

That is quite kind of you.  Thanks for sharing!

AI programming assistance is allowed, but please don't try to "vibe code" your way through making a game or you won't really level up your skills :)

https://discord.gg/NSS4Wfy8V

Web games are allowed.  If your sprites are not created with "generative AI", then that's fine too.