1. If you can budget it, the Mac2Music for 500-600 more than the stock Mini seems to me good value by the standards of this hobby. Had it been available when I bought my Macbook, I would have done it. You will need to budget more for storage, I think.
2. I think PureMusic, at 100 bucks, is very good value; pretty hard to spend 100 bucks an get that much audible improvement, IME. Newer versions much less twitchy.
3. computeraudiophile.com excellent resource.
John