New jam, new experience. And themes?

Hello everyone, this is the third time we participate to LD. We are sure to go ahed with unity but here I'd like to ask you for advice to find a nice source fo audio/fx assets, maybe a tool for creating sounds or some free to use database. We have no real clue on the right path to follow.

PS. Am I the only one that kinda feel that themes are for a big part the same as the last ldjam?