To respond to your question, you might want to call customer service to ask if the battery cover is available as a replacement part. I suspect not; they only seem geared to replace entire Kindles, but it's worth a call if that's what you want.
As for the Velcro, I believe I read that we have members who have Oberons both with and without velcro and I don't believe they had a problem putting a velcro'd Kindle in a cover with corners.
If you do call CS, let us know the answer!
Betsy