If you have a second tub you can just move the whole lid with plants and rest it on the second tub.

Or you can have 2 rez and move the plants to the second one and you are back in business in like 3 min at most. Then clean out the last one you had been using and it will be ready for the next time.

No you don't need to have air stones but it's a good idea even in an ebb & flow system. The extra oxygen and added bonus of having the air stones keep your nutrients mixed up is a good thing too.