Powering RC Servos using Switching Power Supply
According to a comment in your link, the maximum draw is 3A, so 3 could draw as much as 9A. That's 68W so your 75W supply appears to be adequate, at least to the extent the 3A represents a peak draw. To be 100% sure I'd like to see an official spec from the manufacturer that this represents stall current. 

Chances are you'll not be running all three simultaneously at full load so I think you're probably okay. A supply like that (and it is from a reputable manufacturer- Meanwell) should gracefully current limit. 

No you do not (should not) put a resistor in series, just connect them to the supply (observing polarity, of course, or you'll probably be ordering more of those nice servos). 

By the way, you're apparently using a proper distributor (Mouser) so no worries, but I have seen counterfeit Meanwell supplies on the market so be careful with supplies outside official channels.