Does a 700c wheel help you go faster?
The increased weight of the larger wheel (if indeed it does increase) will of course add weight to the bike, but additional weight adds very little rolling resistance (though it does of course affect hill climbing).

It is a myth that "rotating mass slows you down".  In terms of top speed there's no difference between weight on the wheel rim and weight anywhere else on the bike.  Added weight on the wheel rim does reduce acceleration, but 10 grams on the wheel rim only has the acceleration-limiting effect of 20 grams elsewhere -- it's not really enough to notice.  (And once you've accelerated to speed this effect goes away.)

A larger wheel can ride over slight irregularities in the road with less energy expenditure, and so can be more efficient (and less tiring) in some circumstances.  And a larger wheel generally is more stable (though at the expense of maneuverability).