1. I'd say $2000-$3000 minimum, for someone who has never done anything like this, you will have to get an exhaust manifold made, get a decent carb set-up, and inspect/rebuild motor, plus doing all the other mods required like oil returns, lines, bigger exhaust, piping/cooler/airbox for carbs etc.

2. Not the best person to comment, but i'd chuck a starter in it and check compression after changing the oil, then pull down the sump pan and rocker cover and inspect the general condition. Also check the oil for cheese incase of broken head gasket etc.

3. Dunno at all, see what more experienced people use.

4. Forums/ebay/machine shops, ask for something more specific.

5. Dunno :D