Hi Jerilee, I think you could get lots of answers and opinions on supers.

You can remove a full one, or remove and replace the full super frames, and you can certainly add a new super box on top of the one the bees are working on.

Yes, definitely remove the overwinter burlap insulation so air can circulate and hives can breathe in hot summer temps. in these extraordinarily hot days, it's helpful to add an empty hive body or super box and or shim a bit of space on the upper cover so the hottest air can rise on out of the hive. (Especially if your colony takes direct sunlight.)