HelloCustomer and welcome to JA,
Most likely it is gonna be your temp sending unit in the the radiator hose, a lot of VW jettas have that issue. What it does is not make the engine fire ( Spark ) . Did you read the OBD codes ? This temp sending error won't show nine out of ten times. About your windows , most likely the switch in door is bad, but let VW specialist scan it and reset it maybe it will correct then. The windows switch is about 112 usd and the temp sending unit is around 30 usd. Good luck
look at top radiator hose which come of the radiator and follow it close to the engine you will see it it has either two or four wires to it . It has also a spring clip which you need to remove so you can pull the sensor out and replace it with a new one. I am home now but tomorrow i can send sent you a picture of it . Good luck
It is gonna fix it , just like the dme relay will fix the porsche ( you probably had a 944 or 911 with this problem. I'll send you the pic tomorrow. Best thing is to get the sensor from the dealer, aftermarket is not that good.