Thanks for contributing. Here are a couple of answers to your questions/ideas:
(a) As much as we would love to be able to accept album art from users, the record labels get twitchy about this subject. I'd like for us to offer a way to do that, but it may involve some technical work on our end as well as a discussion with our legal team to make sure we're doing it on the up-and-up.
(b) We have plans to expose the Artist ID on the site in an upcoming release.