It can. But the inverse square law makes it not as useful as you might think. What you want is a maser.
Microwave radiation isn't ionizing. That's the bad stuff. Once you leave the path of the radiation there will be no lingering effects other than burns you suffered while in the path. Microwave ovens were initially built to REVIVE cryogenically frozen hamsters. FCC questions can depend a lot on what's in your proximity. Urban or suburban environment, be careful. If you're on the back 40 they probably won't care unless you've leased part of the property for a microwave transmitter tower.