Figure out if I have gas or electric heating
Actually, the old thermostat DOES have a "gas/electric heat" jumper.   It's labeled "JP2" and the "HG" setting is for gas.  The "HE" setting is for electric.   It appears to be the exact same thing, just poorly labeled. 

Look closely (don't touch) and its setting should be apparent.  

A Google search revealed the manual in PDF  as the #1 result and section 2.4 discusses the JP2 jumper.

P.S. Another way to find out if you have electric heat is go to your electric service panel and look at the labels on the breakers.  For electric heat, it would be one of the large (double-wide) breakers.  Turn the breaker off and see if your heat still works.  The thermostat should continue to work, because it is fed from a 120V circuit (which uses a single-wide breaker).

If the breakers are not labeled, you know electric heat must be a double-breaker.  You can find it by trial and error.  Generally it won't do any harm to turn a double-breaker off.  They control a single device: air conditioner, water heater, and the like.  That device will stop working and that is all. I would label what you can. 

(now in older homes or ones with well-wired outbuildings, sometimes a double breaker actually feeds a sub-panel, which has many other things running off it.  I don't see that as likely in a new-build California home.)