I'm new to the RV scene and wondering about a few of our California laws.
Like others drinking in the back of a motorhome while I'm driving, or carring weapons.
Anyone have answers or know where to look these things up?

No problem with open containers, as long as they are in the "living quarters" of the RV. This means basically anything behind the imaginary line separating the driving compartment and the rest of the rv.

Concealable firearms must be stored in a locked case...there is no exception for RV while travelling that I know of.

Once you are set up and camping somewhere, then the RV becomes your "temporary home", in which case carrying concealed is perfectly legal within your rv and immediate camping area.

State laws can be trumped by federal laws though, so camping areas may be governed by different gun laws, FYI