ICX7150-C12P-2X1G – Stacking two of these and connecting – idiots guide please!!

Hi there and thanks to those on this Forum who have helped me get this far with my Network Plan.I was recommended that only four R720 APs should be loaded onto my ICX7150-C12P switch due to power budget constraints, so I decided to order a second one.The ICX7150-C12P switch has C1 and C2, and X1 and X2 ports on the right.  I see X1 and X2 are used for stacking.My question is, given my planned set up in pic attached, do I need to connect via X1 and X2 and stack?  What would the advantage be?  Would this enable me to better manage the power budget?A second absolute beginner’s question to PoE switches…what can C1 and C2 be used for in a normal set up?  Can these be used as non-PoE Ethernet ports?  Finally – am I doing anything stupid with my planned network set up per the diagram?Many thanks