Hi and welcome,
Your projects seem possible.
Relays...
If you don't want to use transistors, you will need DC solid state relays.
With a magnetic/coil relay you'll need a transistor since they draw more current
as your arduino can handle.
With multiple coil relays an uln2803-chip may be nice since it has ttl-level inputs and can be connected directly to your arduino-pins. You'll need an flyback diode using coil relays, which is integrated in the chip as well.
Temperature sensor, I haven't worked with an X2, but I guess you could use most kinds of temperature sensors. Making 'm waterproof isn't hard and can be done with glue, epoxy or even 3-4 layers of paint.
RFID, 3 meters is quite a lot, a reader may be quite expensive. Using 2 bluetooth modules or an 433MHz transmitter+receiver is probably less expensive.
Compass, you can buy a single compass, but for a few bucks more you can buy a 9 or 10 DOF-module, housing compass, accelerometer and gyroscope. Besides direction you could record your driving style as well.If you live in the mountains, you can measure altitude as well.
Automatic lights, it will probably require more... of your attention as usual. If it's still light when you park your car and the switch is still in automatic-mode, you may need to ask your neighbours to push-start the car next morning.....