To answer your original questions.
1-yes
2-it doesn't have to be brand specific
3-the same caliper is used for front and rear
You didn't ask, but I agree that your chosen crankset will probably not work on that frame. The bottom bracket is 68mm, so that will work with the road cransket, but the crank arms probably wont clear the chainstays. The distance between the crankarms on most Shimano road doubles is 116mm. Measure the distance across the chainstays at 170-175mm back from the center of the bottom bracket. If it is more than 110mm, you don't have enough clearance to use that crankset.