1)The Schwinn will be nice, I have one too!
2) If you already have a crank on there use that, it most likely will work out just fine. If it is visibly off when you assemble the bike then you can think about changes.
3)Are you experienced in truing wheels or ever built a wheel? If not, I suggest you just pay to have to done right and practice on something else. You don't "dish as needed", dishing is centering the rim on the hub. If a properly dished wheel sits off center in the frame then the frame is out of alignment.