Hi there.
I was looking at the manta earlier this week, but I hate the side panels. Ended up going for the enthoo evolv ITX.
Manta:
Front: 2 x 140/120mm (2 x 120mm included)
Top: 2 x 140/120mm
Rear: 1 x 120mm (Included)
For you, I'd place the Corsair water cooler on the topmost front fan slot, so cool air can be pulled in from outside and hot air immediately removed by the two top fans (buy some for this)
The NZXT manta has a built-in fan controller (read the manual before using it, you NEED to connect it to a CPU_Fan header)
The fan controller can control up to 8 fans, and most Mini-ITX motherboards have 2x fan headers.
So in total, your case controller/motherboard can support 9 fans.