I dont really think it needs to be aereated unless it sits for a really long time. Toping off with additives (baking soda, calcium chloride etc) should only be done if you are testing the levels and making sure they stay within their proper ranges.
Personally I do. Not an air stone per se`. I have about 8 - 9gal resevoir in a plastic trash can. There's a float valve at the top of that and an auto shut-off valve I installed on my RO/DI. Then of course I have an ATO switch in my sump (I used the dual switch one from autotopoff.com) and an aqua lifter pump for my ATO out of the resivoir. I have about a 500gph pump in the bottom of the resevoir to keep the water circulating good plus I have a heater in there as well. What I like about this setup is that my water change water is always ready. Just have to pump it into a bucket and add salt. It doesn't take me any time at all now to do a water change. And by the time the water change and clean-up is done, the resevoir is pretty darn close to topped off again from the 100gpd RO/DI.