I gotta admit, if I had some 17 yr old kid asking me 8 billion questions and who has no gameplan at all for the car while I'm trying to run a shop and sell a car, I'd be an ass too. If he wanted to plan the project and find all the parts for it, he'd prolly just build the car up. Act like you're serious, I bet he'll be serious with you. Act like a tire-kicker with big dreams and no idea how to accomplish them, then he's gonna treat you like one.
If I were you, I'd step back, assess my skill level, my purpose for buying the car and then contact a seller when you're ready to buy. Not trying to be a dick, but selling cars on craigslist is the biggest pain in the balls and modified cars are even worse.