Can i use wireless control with a networked CS18 and SL32RML?

I have a SL32RML and a CS18. I normally mix from FOH with my ipad (forgoing the CS18). I have a few gigs lined up where i will need to use both. I will need to use the CS18 side stage to control monitors and the ipad FOH for the main mix. My current setup is:

SL32RML--> firewire'd to my Macbook Air (for SMAART and Capture)

SL32RML--->etheet link to my Wi-fi router---> ipad on the W-fi router.

If i add in the CS18, do i need an etheet switcher box with PoE, like the new SW5E? and if i add the switcher box with PoE what does that PoE provide power for? can i forgo plugging the 32RM into and actual power source?