1. not worth it. "quality DIY job" will involve auto-quality paints from an auto body supply shop and an air gun, ending up costing well over the cost of a powdercoat. A typical black coat is $80-$150 for frame plus fork. You can ask to get the decals installed before a clearcoat.

You can use rattlecans with mixed success, but in general expect chipping from abuse.

2. doesn't matter entirely, you can easily find brakes long enough, tires are a little harder to find. If the original 27s are designed for wide (1.5") tires you might want 700c wheels to fit normal-width (and normal-diameter, of course) tires.

3. correct.

4. velospace, fixedgeargallery, search function

5. maybe, probably. if you're getting "grease tattoos" you're not doing it rite. either your chain is poorly lubed with the wrong type of lube (creating tons of grease), you ride city streets after rainstorms every day, or your foot positioning is angled in to the point where your calf is always close to the chain. mainly your chain needs a proper cleaning and lube.

6. i don't care and no one else does, either. put what you want on your bike, especially when it clearly adds function.