All traffic over I2P is encrypted unless you use an outproxy (which isn’t as common as a Tor exit node is), so no. Most, if not all I2P torrenting traffic never touches an outproxy, just like Tor hidden services (.onion sites and whatnot) never touch an exit node.

Hosting a Tor relay is fine even, as you are still just passing encrypted data around. It’s running an exit node that can get you into some sketchy waters with your ISP/law enforcement.

If this was the first time the world heard of onion routing, then yes.

Now they can realize that you’re probably just one step in the chain. And with i2p there’s no way to know if they even reached the end of the chain (provided you host i2p for long enough).