These fans are 120mm.
120mm is standard size.
For a MD Tower like yours you only gotta he careful if your planning on going bigger than that. But you shouldn't need to go bigger anyways. These coolerMasters pack a punch...
I put 2 of them on my radiator for my CPU and now my processor idles 10°C or less.
Your corsair case looks like it has a place for side panel fans.
If your main focus is you gpu, have one intake on the lower side panel.
Sleeve bearings are the "economy fan", they will not perform at the same level as ball bearing and fluid bearing fans can.
Your motherboard supports 5 fans total. One of them is your cpu cooler and you can make the other one also for cpu cooler but many people use it for the top or back fan as well which will then allow it to pull air out at the same speed level as the cpu fan.
Your case comes with 1 front intake fan and 1 back exahust fan, as far as the quality/type of fans I am not certian, and cant find any specific information about it on corsair's website. You can keep those two fans and if you dont like them you can upgrade them. You will want 1 intake and 1 back like the case has, and having 1 at top and 1 at side would be usefull.
You can either use the cpu_opt fan header like i suggested, or use a fan splitter cable.
You can use the 3pin to molex connectors and power it through your psu, but then the fan will be going 100% the entire time, where if you use the fan header the mobo can regulate the speed.