Hi, Welcome
There are a few people that have used Xarcade/HotRod joysticks on their machine. I (and many others here it seems) think that it looks terrible slapping a joystick on a machine, but it WILL work just fine if thats what you'd like.
The electronics side of things really isn't that difficult at all. If you can build the cabinet, you can wire it. Don't hack a keyboard, get an encoder. That way, its just screw terminals and quick disconnects. If you can follow wires, use a screwdriver, and push disconnects onto metal tabs, you're 90% there. It really isn't hard and you can make the control panel EXACTLY like you want.
The monitors like the D9200 will hook directly up to your PC. If you wanted to use a regular arcade monitor you could use an arcadeVGA card as well. Again, it's pretty simple to hook up once you understand what each part is doing.
As for monitor size, most classics used a 19" monitor, either vertiacl or horizontal. A lot of fighters and newer games use 25"/27" monitors. Then there are the showcase and projection cabs with the monster monitors. There are a ton of NeoGeo cab styles, and I think there have been Neos with 19/25/27 and probably more sizes of monitors.
You might be able to find a monitor locally, but perhaps not a new one. If you're getting a new SVGA one, you'll prolly have to go through a dealer.