If you are in the Chicago area you should be able to get a paid technician without too much trouble. You will learn to do a lot of the little things, it is part of the funfun. But having the a tech to get you out of trouble is a nice safety net to have.

You're going to get 100 different opinions from 100 different people about where to start in this hobby. I would suggest keeping it simple...

Buy a game you really enjoy, with enough depth to keep it interesting.
Get a common game that you can get replacement parts for.
Accept you may lose 10% of the game price, its not an investment.
Be prepared to call a tech and spend a couple of hundred when something breaks. More if it is an exotic or expensive component.
Consider going cheaper and getting two machines. That way when one breaks you can still play the other. And you won't be as nervous when you try and work on them yourselves.