HELP! MEMORY UPGRADE FOR CORSAIR ONE PRO i180?

[MROL1]

Hi - help needed looking for a memory upgrade on my One Pro i180. it has the Asrock X299E-ITX/ac motherboard which says up to DDR4 4000 memory!? 

But wanted to ask with the standard 2666 memory can I add  Corsair Vengeance 4x16GB SODIMM DDR4 2666 MHz and if each module bought separately then installed as 4 pieces does that utilize the quad channel ability of the motherboard or do I need to fid a 64gb 4x16gb kit?

Finally there seems to be a quad kit for Corsair Vengeance 84gb  SODIMM DDR4 3200 MHz.. would that work would it downclock it to 2666 or is the motherboard capable of using the higher performance?

With Thanks

Mark