Re: Microwave and gen.
When circuiting a home we use a rule of thumb: the full load on that circuit should not exceed 80% of the breaker rating. A 15 amp breaker should have no more than 12 amps of load. A load is anything that draws (consumes) electrical power. Volts x Amps = Watts
Your generator is rated at 1000 watts. Your microwave is rated at 700 watts (if you got that figure off the stamped plate or load label on the unit). Therefore your load is 70% of the rated load of the generator. You should be just fine.
If your generator has a breaker on it, check to see if it's rated at 7.5 amps or more. Your 700 watt micro should draw a little less than 6 amps at full power. If so, you are okay to zap away.