I'm going to suggest:
A) browsing your state forum; your questions have probably already been addressed there
B) if you can't find the answers, re-post your questions in the appropriate state forum, since you are asking about state (and possibly local) laws.
For an overview on many topics, click on the "maps" button at the top of the page, then on the specific topic, and see what color your state is.
WalMart corporate policy is to follow state law. So if OC is legal without a permit, you can carry openly in Wally World now. If a "manager" (more likely a low-level supervisor) gives you any grief, remind her/him that corporate policy allows this. If there's still a problem, get the person's name, and the store manager's name & phone #, & (if they'll give it to you) the name & phone of the area supervisor. Then leave peacefully (leave your cart right there, where they stopped you), go home & make some phone calls.
Nationwide, within your own house & on your own property you can do just about anything. (No, I don't mean crimes against other people, but freely exercise your rights.) You have MUCH stronger protections against gov't intrusion than you do when out & about.