It'll most likely be something like "My Own Prison" "What's This Life For" or "With Arms Wide Open." Gotta remember, for labels any tracks that aren't on official albums are considered 'rare' or 'previously unreleased.' It may not hold true for fans who find everything, but for the general public... As a music fan who actually does buy vinyl, I'm hoping to pick this up the morning of RSD to add to my collection of Creed vinyl.
Is this only available at certain stores or can we buy it online?
Only at small independent record stores only. Hence why it's a Record Store Day exclusive. RSD is a very big deal, so you'll probably want to wake up mega early and stand in line outside of the store in hopes to get it because some stores only gte 1 or 2 of them and they are un-orderable once they're gone.