Yes Walmart Neighborhood Market SUPERMARKET is the only place you can buy Walmart gift cards that's counts as grocery at 6% with AMex BCP.
I buy $200-400 at a time and use it at Walmart, Sams Club and for Sams gas.
Yes Sam's Club takes walmart cards and MC and DIscover, no visa or AMEX.
Walmart takes everyone except maybe sam's credit card not sure just got my sam's credit card
I have a regular Sam's Club store card(not the Discover version), and I use it all the time at Wal-Mart. I can even get WM gift cards to use at the Murphy gas station to get the discount.