CAPWAP and user data split from AP

I am reviewing the manual, and deployment options; however, Is CAPWAP a protocol or a tunnel encapsulation? I have seen it mention that 'all' data is encapsulated in the CAPWAP tunnel, so due to the latter, should I lower the MTU/MSS size?

Is there a way to get user traffic not encapsulated with CAPWAP, and only the management/controller traffic from Wireless controller to AP using or encapsulated in CAPWAP?

I am not fully understanding the CAPWAP and deployment concepts.