Clarification on Right of Redemption in Alabama

[Cooper B.]

I'm hoping someone can help provide some clarity to me regarding the right of redemption law in Alabama.

Say a property is foreclosed and sold back to the bank on the courthouse steps.  The bank turns around and sells the property to a 3rd party for a lesser amount.  If, still within 1 year from the original foreclosure sale, the prior owner elects to redeem the property, would they owe the 3rd party the amount that the bank bid to originally take back the property?  Or, would they owe what the 3rd party had paid to purchase the property from the bank?

I realize that the owner of the right of redemption would also owe interest, taxes, insurance premiums, and "necessary permanent improvements".  What constitutes a necessary permanent improvement?