You're going to have the problem of people using other's music in order to attract donations somewhat anonymously, so you will want comments near to the donation address so any offenders can be called out and people can read what others are saying before they donate. But donations for good music is a good concept, so best of luck with it.
The Magic Internet Money picture is from Reddit /r/Bitcoin - Sometimes its displayed on the front page, pretty awesome logo, so we decided to link it over to the Bitcoin Reddit as well.
As for the anon artist posts, well we were hoping that anyone uploading tracks to Soundcloud should be aware Soundcloud makes them sign something saying that they are the original copyright owners of the music, I see what your saying though. As for submissions, so far people have been emailing us, we visit their Soundcloud page and look it over to make sure. I don't think this sort of thing would happen very often, but its definitely possible. I think a comment space beneath would be awesome, just not the best at html, so not sure how to go about that.