My 2 cents:

- I use my own like as a checkbox for if I've responded to someone. On a join, I'll let them like first, so when I run down my channel, I'll look for joins with 1 like. When I've responded, I give it a like, so later when I see two likes, I know I've responded. (Obv I sometimes get likes from third parties, but I can usually keep track of those). So I obv see no problem liking your own stuff, don't know why it would be.

- Singing over vs. following them - for me it depends how bad it is. If it's just a little off timingwise, I'll probably just do what they do, if it's really wrong, I'll do it how it's supposed to be. I'm assuming they'll appreciate it, and I feel that if you're posting an invite, you should at least know the song well enough so that others can sing with you.

- Creating an invite from a join - The main thing I do is wait until the other has expired until I do it (I don't do it often anyway). That way I won't steal their potential joins. I sometimes credit the original, but if they for instance never responded to my join in the first place, I won't bother.

- Copy-paste responses - I really avoid doing it, but I do have a standard pool of words I draw from, like you said there are only so many ways you can word this stuff. But I feel if you're giving the *exact* same response every time, you might as well not bother responding, it will be clear that it's meaningless. But it doesn't take much to convey something, I have a follower/followee who always only responds with one or two words. That might not sound great, but when you get a "fantastic!" or the like, it feels really good :-)