I can answer part of these questions.
We currently only have an App for Android in development, mainly because... well, Matt doesn't own a Mac to code on. We were working on a mobile site for a bit and as far as I know, someone was lined up to take over coding of it, but I'm not sure if that deal fell through. We would love to have an iPhone App for all the Apple nerds too, but for now we are stuck w/ a non-mobile friendly site and an Android only app.
As far as the importing your collection goes, that'll have to wait for Matt to answer...
But welcome to the site and I'm glad you are enjoying it so far. We aim to be as user friendly as possible, so if you notice any problems let us know.