If the feed seems to be stagnant, you could be using the (default in many cases) active sort, which tends to have a lot of the same posts at the top, from what I've seen. Switching the sort to hot generally shows more fresh content in my experience. You can block communities on the web version using the red button on the right, in what I think is the sidebar, although that might be hidden on a phone. This site looks to be helpful for finding communities as well.

I think what OP is talking about is the ability to generate TOTPs, which requires a paid plan.

Nope, still not visible. You can see it in Thunder?

I uninstalled my reddit client and put my Lemmy client in its place on my home screen so the muscle memory doesn't have to change. Here's hoping the communities end up being a feasible replacement!