1) Yes, different cranks have different main bearing sizes but the standard 302 is 2.249. Your block should be set up for that so I'd stick with that size.
2) You probably could throw one together but it would be silly. I would have everything checked to make sure the crank is balanced correctly to the total bobweight.
3) A good set of dial bore gauges, a 1-2 and 2-3 micrometers, ring compressor, torque wrench, degree wheel, dial indicator... That will get you started.
4) It depends on what the stroke of the crank is. CR has nothing to do with cubic inch.
5) If you are talking about the Fel Pro Locwires, I dont recommend them. I'd recommend Cometics which are Multi Layer Steel and dont require a receiver groove in the head, nor o-ringing of the block.
Once you have all of your parts bought you should take them to a competent machine shop so they can check the deck height and the bore sizes. For parts I'd talk to Wild Bill at Pro Power in Ft. Lauderdale.
http://www.propowerparts.com/ They are good guys to deal with and they can sell you a very good 331 or 347 stroker kit. What pullies are you going to be using with your S-Trim? If you decide to sell the A-4, you have a buyer right here.
Andy