No credit card required
Browse credit cards from a variety of issuers to see if there's a better card for you.
Depends on what you mean "go into Lowe's". Yes they stack; but as far as I've ever seen, you only get the ShopDiscover cashback if linking through the ShopDiscover mall to the retailer's website and purchase online. So with ShopDiscover and the UR Mall, I start at the ShopDiscover or UR Mall portal, clickthrough to the retailers website, then checkout using gift cards and the portal administrator's credit card (this part only matters if the retailer doesn't report the referral...so to be safe I usually put a few dollars on their credit card).