the store that Namoi works at "Food Circus" was it supposed to be a convenice store such as 7-11 or was it a super market I've kinda fuzzie on that point

Food Circus was a supermaket !!!

The episode about Mama finding a dirty magazine in his room, one scene had Mama, Iola, and Aunt Effey protesting Food Circus's descision to sell such "smut". You can seen signs advertsing "double coupons", convience stores for the most part dont do that.

also in another episode that dealt with Naomi's boss making a pass on her, her boss in his office is on a mic talking about something being marked down plus you can see a rather large window in the background that appears to be looking down on the floor, like many supermarkets have so the boss can keep an eye on the customers and employees.

and yet in another show, Bubba tells Mama he got a job working at Food Circus unloading trucks , though he would get fired later on after dropping a case of beans ( I think ) on his boss's foot.
Convience stores usually are too small to hire someone just to unload trucks. Most convience stores you do everything from making the food, unloading the trucks, and of course taking care of the customers. I used to work in one years ago. The worst job I ever had.