1. Count the number of teeth on the chainrings. A combination of 52-42 or 52-40 is fairly typical.

2. I would use the cheap KMC 5-6 speed chain. The last time I bought one it was about $8 at a local bike shop, although it was not in a high cost region of the Country.

3. A crank length of 190 mm is really long. More typically you'll find 165-175 mm. You'll probably want to be towards the upper end there.

4. If you're going with a cotterless crank, you'll need a new bottom bracket. Luckily, Velo-Orange now supplies a modern style cartridge in the French threading standard.

I'm not that familiar with the cottered crank aspect of your inquiry, so I'll leave that for others to sort out.


edit: Are you planning on putting the rear brake back on? I recommend that you do.