Hi krazypara3165
I had a beer engine for a short while until I sold it to a local landlord, I've seen the gas pumps on the wall down in beer cellars but I think they're not needed for home brewing as we tend to have short beer lines and the hand pump will easily draw beer from a keg a few meters away, in fact you'll find the beer will pump itself if you have it connected to a pressurised keg!
Make sure you have a check valve fitted just before your hand pump, this will only allow beer to flow from the keg through the pump when you pull the pump, otherwise it will just pour continuously if there's pressure from the keg.