Hardware Suggestions for MAME

I poked around this forum (albeit not very deeply) looking for the answer to the following. If I missed the thread(s) that cover my questions, sorry in adavnce. If someone could point me to threads or web sites that could give me details, I'd appreciate it.

I have been out of MAME since 2005, and am ready to get back into it. Obviously a lot has changed since then, and since my old arcade computer died, I have to start from scratch. The only thing I have is my old Joust cabinet and custom control panel. This mean downloading everything all over again (software, roms, etc), investing in a new computer system, new keyboard controller, probably new display, etc.

I'm looking for advise on what I should do for hardware. My plan is to first buy a 2TB USB hard drive and download / configure everything on it, then eventually add a new computer system, monitor, etc. Here are my questions (so far).
- what is recommended for hardware. Last I heard, the more powerful the CPU and the more the RAM, the better. Is 32GB of RAM overkill? Although I plan to play mostly 80's games, which ran fine on an old Pentium, I still want the option to play the latest that MAME has. Back thenm a powerful graphics card wasn't important....is that still the case? Would a server grade machine be better than a desktop? Should I build my own system from scratch by purchasing the motherboard/CPU/RAM/etc separately instead of a pre-build system from Best Buy/etc? I have a lot of experience in building and configuring computers from scratch, so that isn't an issue.
- How much disk space does MAME currently require, including ROMs, CHDs, sound files, etc. I plan to transfer the 2TB USB drive out of the USB case and straight to the mother board, or else buy a separate 2TB drive for the arcade machine's motherboard. Is 2TB too much?
- What would be the best operating system. This is worse than asking religious questions, but is there an advantage in Windows 7, Windows 8, Linux (which flavor), etc? Is one OS faster at MAME than another (are there benchmark test)?
- My old cabinet had a 21" CRT, which is pretty much unseen now-a-days, and considering age/storage, might not work anymore. Is there a recommendation for monitors? Way back when, light guns for shooting games didn't work with flat screens. Is that still an issue?
- I'm open to suggestions on spinners, track balls, joy sticks, light guns, etc.
- As I am pretty much starting from scratch, I plan to replace my keyboard controller, so suggestions are welcomed.
- Anyone have experience with solid state drives? Does it make a difference with CHD based games? Are they worth it at all for MAME?

Thanks in advance for your suggestions. I'm sure there will be more questions. I'm in no hurry to build the system, so I might not start until MAME .150, but I just wanted to get ready with things now.

MiniYoda