I don't really like those air stones like that that curl up in the bottom--they never seem to last long and they are hard to keep in the bottom of the bucket. You may have to experiment to find air stones that last and provide enough aeration for 5 gal buckets. Like I said, I run 2 stones per bucket. Do you have pH meters? Those strips or liquid are most people use with aquariums are not accurate enough for hydro.
I do not use RDWC because of the need to have all the same strain (or very compatible strains) because they are all getting the same food and the same height of plants as you cannot raise or lower any buckets. Unfortunately this makes it necessary to create a canopy at the height of the shortest plant. For a small space and just starting out, you might want to try individual buckets and then make them recirc as you get a little more familiar with your plants. One disaster can kill your plants and when recircing, if it is nute related in any way, all your plants can suffer. Also with individual buckets, you will have the opportunity to experiment some and see what level of nutes your plants like best, you can learn canopy management. I really really like to clean out all the buckets on a regular basis and inspect the root systems of the plants. This is another thing that will be hard with a RDWC. Please give it some thought before you connect all these buckets together and start adding water pumps.