Lemmy doesn't have shadow bans. The other instances also don't know what IP you posted from. Only your own instance can see that.

I know others already answered you, but I just wanted to explain further. That's the main advantage of Lemmy: being federated. It means that each instance, even though they communicate with each other, is independent (they have their own rules, their own userbase, and are hosted in their own servers), which means that, even if one decides to ban people for using Tor, others wouldn't follow through. Dbzer0 wouldn't punish you for it though.

Depends on the instance.

Again: any given instance could do that – or not. There is nothing about Lemmy, the piece of software, that either requires or prohibits instances from having such a policy.