as far as dimensions go DON'T measure your cabinet. Instead measure your doors and hall ways. Make sure that the cabinet you construct can be moved around your house or apt. This happened to me(well my nephew in college)... please don't laugh. After seeing my cabinet he had to have one. He was in a single 1 bedroom apartment in college. He did all the research in the world, measured twice etc. He built his cabinet in a friends garage exactly like his favorite arcade cabinet. When he took it to his apartment, there were a section of stairs that the cabinet would not physically fit through. HE COULD NOT GET THE DAMN THING IN HIS DOOR! Of course his friend was more than happy to keep his cabinet at his house till he moved out (he was a graduating senior in like 3 mos).
So if you are building from scratch I would use other cabinets as a guideline not a template. Incorporate the ability to move the cabinet in your design.
Most cabinets are<30in because of the standard door sizes. Those that are not have removable control panels. For the stand you plan to build width should not be an issue. Because if it is too wide for the door you can always turn it sideways. Similar to the big showcase cabinets (or whatever they are called)
ok I've rambled enough. Hopefully I've answered your questions.