Black grease like substance kia rio

I'm trying to fix my old forgotton car step by step.. my main concern is the black greasy substance under fan belt over certain parts under the hood of the car (engine parts?) please check attached pictures

note: engine oil color / smoke from exhausts etc seems ok and no signs of leakage

other problems im having in the car (it might help)

Once forgot to fully tighten radiator cap but immediately stopped and refilled water after seeing the temperature gauge
ABS light on and battery drained flat one time
Squeaking like belt noise
One blown out A/c valve as per one mechanic
RPM not working (crank shaft sensor ?)

Please advice where to start the repair.. Also check attached pictures.

Thanks