Publicly viewable are your posts, comments, and possibly votes too.
Your instance admin and the remote instance's admins. That might also become entirely public if they want to solve the subscription counts sync between instances as well.
The votes are public.
Votes will basically give away which communities you are using then.
Your fetish is safe between you and your admin.
Visible to you and your instance admin.
Publicly viewable are your posts, comments, and possibly votes too.
Your instance admin and the remote instance's admins. That might also become entirely public if they want to solve the subscription counts sync between instances as well.
The votes are public.
Votes will basically give away which communities you are using then.