do you still need to know stuff??? 1/2" conduit you can fit 12/2 in it....thats about it....220 needs 12/3 to be done properly (fire codes), however, if you live in the boondocks or something where there are very little fire codes, you can wire a 220 with 12/2....the guage of the wire would depend on the breaker as well....12 guage is only good up to 20 amps.
I ran 3/4 emt in my garage, makes it real easy to pull and leaves a bit of room if you want to add something later or up the amperage.
not sure how your code is, but here in Ma. you cant run 110 and 220 in the same box, but you can run the 220 to a box and then take the 110 off of that to continue.