Yes, sounds like you have some electrical "issues". Doesn't make sense to have 14 VDC at the batteries and 18 up front-- there is nothing up there that can "make" voltage. If you are not comfortable troubleshooting the 12 VDC system, probably need to have someone experienced with them help you.
And, you need to determine exactly what temperature you are reading-- likely COOLANT TEMPERATURE. And your 90-150 degrees F (assuming the engine is fully warmed up) indicates a bad thermostat(s). If this is not a gauge issue related to your voltage issue, you need to get that addressed ASAP.
