we just wired the new part of our garage for 220V.. you need 2 breakers like sharpxman said. they do make them as a single unit double wide but either way it has to take 2"spaces" in the breaker box... and you should have 4 wires (4th is a ground) but for low amp for short runs you can "ignore" the ground and go with 3 wires (this is not optimal, but it is how we wired up our air compressor but the rest is 4 wire for our stick arch welder.)
yep, it's a double size breaker (double wide), the single only gives you 120v
unless you're in Europe or other parts of the world where you have 220v 1phase circuit
as far as i know you don't need 4 wire cable, 3 will do but the appliances (like stove) are using 4 wires
black, red (these go in the double-breaker), white (neutral) and ground
for 240v like compressor, welder, etc you don't need the neutral but you always use the ground wire