I have a tendency to be long winded, so I'll take the short approach. I've been interested in creating a cab for about 10 years now. Got into MAME back around 2000-2001 and thought about creating the cab then, but didn't have tools, money or know-how. Fast forward 10 years and here I sit. I have the tools, a modest amount of knowledge, but I'm still poor (not sure if that's the one thing I want to have missing!).
I've looked through this forum quite a bit for the past few months. It's obvious there is a wealth of knowledge here, so I thought I'd ask you guys my numerous questions.
I've created the cab, for the most part, based off
Lusid's Arcade Flashback. I did make some alterations to make it fit for me. I'd like to build on that to make it a little bit nicer. I really like Knievel's Neon Mame and Epyx's Alien themed cab. So I might go a little toward that. All that said, I have a number of questions and hope you all can help be through this process.
Here's what it looks like thus far:

1. For the CP, I'm going with a 2-player 6 button setup with 8-way joysticks, with trackball and possibly an additional 4-way with 2 buttons. I'm a wiring noob, but love the look of the led buttons. Is this something I should stay away from with my first cab? I'm a little leery of all the wiring. Does it require both an ipac and a ledwiz?
2. I know this stuff requires extra power, but how do you pull the 5v or 12v power? Does anyone know of a tutorial or walkthrough of any sort on it? That part throws me.
3. Will I need extra fans inside the cab? I'm planning on going with a partially open back to the cab and having one of the sides off of the pc. The design of the cab allows for a ton of room in the bottom. I guess my only concern would be for the monitor and marquee lights.
4. I'm using an older pc with an AMD Athlon 64 processor running at 2.4 ghz with 1G of ram. I intend to stick an ATI 9200 series video card in. Will that be sufficient to run Maximus Arcade and most of the classic arcade games?