Paint & Body Work - how to remove and prevent rust ?

Hi my rear diff cover is rusty looking and some part around it, what can I use to remove those rusty and what spray I need to spray for prevent rust in future ? I live down south, so no snow or salty road, I just dont like the look of rust. THANK !!

POR15 is a rust converter.. its rock hard and can be painted right over rust... but its not UV resistant, so id the part is going to be exposed to direct sunlight, it needs to be cleared. It can be brushed on or sprayed on. :)