Twelve screws should work as long as they conduct the magnetism well. You won't have any issues if you buy Stewmac's polepiece screws, although they are way overpriced.
The handdrill method works quite well. Doubtless you've already seen Jon Fisher's pictures (that's where I got the idea), but here's two pictures of mine for another angle. Notes: I used a clamp to control the speed of the drill. It was pretty effective once I got the hang of it. Also, DON'T mount the spool like I did. Put it in a tupperware container directly below the spinning bobbin. Guide the wire with thumb and finger. The wire won't snag that way.
http://i134.photobucket.com/albums/q119/Ge...ct/100_4672.jpg
http://i134.photobucket.com/albums/q119/Ge...ct/100_4673.jpg
Yes, a typical DMM (digital multimeter) will suffice.
http://www.lowes.com/lowes/lkn?action=prod...;Ntt=multimeter
If you don't care about precision, it isn't strictly necessary to count the number of windings or measure the DC resistance of the coil. If your bobbin is typically sized and you wind it till it's full, it will have a normal output. However, the meter IS useful to make sure your coil is not a short or open circuit. If you get one, set it to 20k ohms to measure.
I suggest potting the coils first. I don't see how the wax can totally penetrate the coil if the coil is already wrapped in tape. I would put the tape on after the wax.
Again, I'll direct you to Stewmac... I know they're expensive, but they are a good source for pickup parts. They have everything you need to make a humbucker, although it's probably more cost-effective to make your own bobbins and baseplate and buy the magnets, polepieces and wire from them.
http://www.stewmac.com/shop/Electronics,_p...ups:_Parts.html
I can't answer that, as I've never built a traditional humbucker. On the pickups I've used, I've soldered the leads to little eyelets that I got for building tube amps. One for each lead, and one 42awg lead goes in each eyelet as well. When you solder, the trick is to heat the eyelet so that the solder melts the insulation on the 42. But if you heat it too hot you'll burn the thin wire and it'll break, so be careful. It is NOT fun to rip a ruined pickup apart and rewind it!
You'll have a blast. I find pickup making as enjoyable as any other aspect of guitarbuilding. and your pickups will sound amazing.