Vacuum Pump Selection, Need Some Advice

Hey all, I’ve been digging around in forums and on Ebay trying to glean all the information I can for selecting a vacuum pump. I’ve still got a few questions, though.

I know guys are having good success with the Robinair and Yellow Jacket pumps. Is there anything specific about these pumps that would lead me to choose them over a similar item?

Also, what are the benefits/disadvantages of piston vs. rotary pumps?

Any specific HP rating I should look for? It seems most are 1/4-1/3hp.

Any help would be much appreciated guys. Thanks!

Also, if there’s anybody in North/West Texas that would be able to spare a little time showing me a few tricks I’d be very grateful.