You wan to clean the salt and stuff off the outside with a toothbrush and warm water. You may need to scrub lightly with a slightly used scotchbrite pad depending on whose reel
you are cleaning. To clean off the grease you will need some sort of solvent, alcohol works ok and isn't too harsh on the plastic parts. For grease you can use most quality waterproof greases, Superlube is a silicone based grease that works well and some guys use lower unit grease. I use grease on gears and shafts and oil on bearings, you may need to re oil the bearings throughout the season.
If you need parts Bucko's in Fall River is a good source, most shops probably have Penn parts available.