So, at some point, I'm planning to make my very own dedi/homecab for my use (when my family actually gets a house and MONEY). It'll run either OpenITG or Stepmania, and I'll try to get a Technomotion like pad for use on all kinds of gamemodes.

How will this work? Up, Down, Left and Right will be for DDR/ITG. Up Left, Up Right, Down Left, Down Right and center will be Pump it Up. EVERY SINGLE ONE will work for Technomotion.
However, to make this work, I'm gonna need some help from some of the engineers here on the forum (if there is any) or tech guys.
The first thing I have to worry about is: Costs.
How much will parts be? How long would it take to build the cabinet if I have to? How much would it take to build a custom 2P arcade pad?
Second thing: Part choices.
What screen should I get? What OS to run things on? IO boards? USB ports? These are things I need to know.
Third thing: Time.
I have a restricted schedule, and so does my dad due to school and work. What would be a good time? I go to bed at 9 PM Sunday-Thursday unless there's other reasons. On Friday and Saturday, it'll be till whenever I have to go to bed.
Fourth: Skills.
I need to learn how to be a craftsman, and how to wire. Is there a way to teach me on how to do things? Or how to protect myself from other hazards?
These are some things I need to know so I can actually get things done. Would appreciate some help, as this is a serious topic. If there's something you know, feel free to let me know, like other websites for resources, or other places to discuss this.
Anyways, thanks for the help if you need it.