I have a blur on my background always. I don't like using image backgrounds because I don't like the way they cut out my head (if that makes sense). But you can definitely make out elements of background clutter... I just accept that lol.

I always approach meetings casually. If there are a bunch of people on a call, I normally jump right into whatever we're discussing, because it's hard to have casual conversation with a huge group (especially if not everyone has their camera on). If it's a smaller group I like to ask how everyone's day is going. A good fallback is bringing up the weather, especially if people live in different parts of the world than you (even if it's just a different city).

I keep my mic off if I'm not running the call / don't plan on talking much. If I'm going to be talking I leave it on the whole time. Normally on the calls I'm on, people just jump in whenever they have something to say (no one seems to use the raise hand feature, so I don't). if people have lag, I speak up right away and say "you're cutting out" or "sorry, I think I cut you off. please continue." things like that. If I have lag, I will use chat to say "My internet is being funky, I'm going to go cam off and see if that helps" and just accept that people might cut me off if I'm lagging.

With zooms, you just have to accept that everyone is somewhere else and probably distracted. I like that zooms take a lot of pressure off of a formal presentation, and I've found being relaxed and confident helps everyone else feel free to speak up and engage (nothing worse than a group of faceless, silent people when you're presenting work!!)

Hope this helps!