Grips/Bar End: On my MTB commuter I use leather ergo-style grips, with mini bar ends. Plenty comfortable, but I don't ride it in the rain..
Tire: Favorites for a bike that might go off road are Conti Travelcontacts, Gatorskin-like slick in the middle and knobbies on the outside if you sink into loose stuff. Great tires, and they look legit on a MTB frame.
Pedals: Thermalite platforms with fixie straps.
Fenders: No, I'll use a different bike if I have to ride on a rainy day, one with thin tires and full wheel fenders. I had a slashguard for a while, hated it.
Lights: Minimal, Knog or RavX USB on the front and superflash under the seat. My commute is plenty well lit, the only purpose lights serve is to attract driver attention.
Rack: My MTB commuter uses a Delta SuperSherpa. Great price, light and has been perfect for my needs. However, if you don't have eyelets, or the disc bracket is in the way, I guess you are going to go the p-clamp or seat clamp route.