Are they the same units used for regular airbrushing with paint or are they something different.
My airbrush is form a hobby shop so it is not specific to cakes but works just fine, I know a big cake decorating company here in sydney used to sell compact systems but not sure of the difference. You just have to make sure the colurs you are using are airbrush ready. I use americolour...actually they sell an airbrush kit.
I have an older one that is also a regular hobby one but only used for cakes. If you are considering buying, I would recommend checking out the noise levels when the compressor is running. Mine is quite loud, but I've seen many that are quieter (just can't afford a new one yet).
You can use a regular compressor and hose. Definitely get a new airbrush though, for sanitary reasons. I would recommend a smaller compressor with a gauge that will allow you to keep the pressure relatively low, not like the one you might have in the garage. Here is the one I have from Amazon:
Most airbrushes are built along the same lines.(except the aztec)
However I try to stay with the more well known brands. The reason is that a really cheap brush might just be cheap because it is made in China, or with re-cycled metals that have lead in them. That scares me. I know that Paasche, Kopy Kake, Airmaster,BAdger, Iwata, Grex, and Americolor are all reliable companies that back their products. Those above are all nickel plated brass.
Don't get a brush that has already been used- it needs to be food color only.
If you have a Tank aircompressor in the Garage, it has a gauge to regulate the air. I prefer the tank one because the air coming thru the hose is smoother- no vibration. You just buy and extension hose and leave the compressor in the garage and just the hose comes in.
If you don't have a compressor, any will work as long as it has a gauge to adjust the air flow.