In the event your mp3s bought from online apple store get deleted, can you downl

Normally no. You can only download them once from iTunes. However, I had a hard drive crash earlier in the year and after asking *very, very politely* Apple was kind enough to let me download my prior purchases again, one and only one more time. So you should ask and remember, be nice! good luck! PS. Also setup a scheduled backup so you wont lose your tunes in the future as I suspect at some point Apple will start telling people "sorry but too bad