The bare wire is called the safety ground, the white wire is the neutral.
Depending on how the recepticles are wired, you may or may not be able to use a single GFCI device. If you can use feed-through the first box to the others, you only need one. If each is run independently, you may not be able to use a single one. Only if you can feed subsequent devices from the load side of the GFCI will they be protected by it. If it branches out from one box, if there isn't a recepticle there, you might find it cheaper to just add one there, and then feed the other lines from the load side of the GFCI.
A 10-3 cable would allow you to use one wire as either a switched leg, to provide 220vac, or to create two independent (shared neutral) circults.