I would probably say fill 'er up. CoolerMaster has its name for a reason; their cases offer great cooling. If it were me (and I love fans) I'd put a fan in every spot I could.
And by coolant do you mean liquid cooled? I would say no. If you liquid cool, the fans won't hurt. If you mean the opposite, that with all the fans, you wouldn't need to, well then that leaves it up to you. The main reason people liquid cool is for it to look cool, be quiet, and be cool. I'd look into the temps you get with air cool before you go and liquid cool.
Thanks! Exactly what I was looking for! I don't want the nightmare possibilities of liquid coolant leaks, and don't mind the fan noise, so again, thank you!