Re: Oiling Rosewood for Dummies.
I like the Gerlitz Guitar Honey. It works quite well in my experience with it--I've been using it for about 10 years.
Another product I like is the Dunlop 65 Guitar Maintenance kit. For about $25, you get the String Cleaner; and the Dunlop 65 Spritz Cleaner/Polish; and the Dunlop 65 Carnauba Wax. For fretboards, you get fingerboard Cleaner/Prep, a fingerboard conditioning oil, and a fret polishing cloth. They are all fine products, and I especially recommend the String Cleaner.
Fret Doctor is highly recommended, though I've not used this product.
You can get a lot of gunk off the fretboard with just a damp cloth, and then wipe it dry. A little bit of toothpaste does work well for polishing frets--just use a damp rag to wipe off the excess, and then buff it dry. I'd follow that with an oil treatment.
My favorite fingerboard product was made by a company called Tres Amigos, back in the '70 and 80's, long out of business. Their Pure Lemon Oil is the best I've ever used, no other "lemon oil" has ever come close. It is a product I truly mourn the passing of.
Bill