Do you already have the LCD panel? Most panels today have mounting holes on back that you could just use standard mounting hardware onto a piece of plywood, attach that to the supports on the cabinet, then put a bezel on.
As far as the control panel goes, contact one of the sites listed in the banner ads at the top of mameworld.com, you're going to be working with fairly standard dimensions there. But to be honest, you might want to spend some time thinking about doing it yourself. You probably will catch the bug the rest of us have, and end up doing swapable panels or modular.
It's *really* not hard. I hadn't touched a saw since I was 6, I'm days away from finishing a custom designed cabinet with a modular panel. It's really easy, all the information is here, or if you'd rather get the information from a centralized location...
http://www.amazon.com/Project-Arcade-Build-Your-Machine/dp/047089153X/ref=sr_1_1?s=books&ie=UTF8&qid=1314513591&sr=1-1Trust me, in the long run it's cheaper. I spent $150 to buy a hotrod prebuilt panel. Then I decided I wanted a trackball, spinner, and flightstick, so I spent $700 on a Slikstick panel. It was too big and unwieldy, so I spent hundreds on swapable panels, but they took up too much space. So then I built a modular table implementation to go in front of my computer desk, but I felt too far away. So now I'm spending more money to do what I should've done the second time when I realized how much fun this was, and just built what I wanted in the first place.
Don't be me, get project arcade and do what you really want the first time

As far as the pullout panel goes, keyboard is usually the best option. A trackball is a mouse so no need for that. You'll need somewhere to mount the Ipac and Optical encoder, but that depends on the implementation of your panel.