Someone answered about the oil.

Either the wiper motor brushes are finished or the negative ground strap is not making good contact. Make sure the motor is bolted down properly. Test for power using a light bulb with wires connected to it.

The OEM horn has no relay. Power goes from fuse 2 via the horn to the ring to the chassis. I guess the contacts inside the horn is welded shut (there should be 2 horns, most likely only 1 is broken, test by connecting only 1 at a time). See my other post about different horns. Suggest you also add a relay when you change the horn, but not absolutely required (coil goes to + power on horn and to ring, contacts go to - power on horn and chassis).

Fuse 5 is for the rear window demister and overdrive. Fuse 3 is for the heater according to my wiring diagram, but I think this should rather be called heater fan. The cigaret lighter is not fused, goes via the ignition switch to the battery.

Have fun...