How do 3d glasses affect your normal vision?

Not at all. 3d glasses, when taken off, should not affect your normal vision. If you wear them all the time, there should also be no effect except one eye may get more glare than the other eye (as each lens polarizes light in a different direction).
Not at all. At least I hope not. The glasses (the active ones) simply alternate differently polarized images to each eye. Its like each eye is watching a slightly different movie from different perspectives with no prism/balance issues etc. There is no lasting or even short term effect.