The auto AK47 should do fine in your AG, two plants will probably be fine as well. However, more than that and you will still run into issues with the size of your water reservoir. The air pump in there will do fine vs. an air stone, they do the same job. If your concern is closet space, either of the links I gave you work fine for closet grows, I can fit two or three 5gal reservoirs in a closet no problem, remember its always better to have more space in the res than you need...if you don't have enough it can be detrimental to your project.
Since you plan on growing in the AG though, you will need some supplemental lighting. The AG lights only put out about 1700Lumens (lumens are a measurement of light output and are what you really need to look at for your grow project). This will be fine to produce buds, however to maximize your yield with a grow space for an AG you will want to have about 3000Lumens of light. This can be achieved by adding (depending on size) one or two CFL's to a light timer. Remember, if you buy CFL's, and you can get them from walmart, you HAVE to get ones that specifically say they output the daylight spectrum, most CFL's produce "soft white" light spectrum, which is regular indoor lighting, this will still provide necessary light, but not the full spectrum that the sun produces. One 1500Lumen daylight CFL will cost you like five bucks....and its definitely worth it.
