If you are going to let it be a download, you'll have to watch for copyright and interllectual property infringement. You may have to state that clearly before people send you the files. As for the files already uploaded to you, you should tell them that. Good thing about streaming is that we don't worry too much about this.
I'm not sure of others, but the reason I don't put all my songs on sites like soundclick is because they let people download. But then, I may be the minority.