rust help

[sweety@nni.com]

Anyone have any suggestions for relatively inexpensive paint that stops rust
and looks decent? Also any suggestions for what to spray on the
undercarriage of a trailer that has a good coat of rust but no serious
damage? I've been considering doing it by brush and roller instead of spray
on the outer shell as it's cheaper and I have seen it done well but forgot
what paint they used....any suggestions ? 
I have this wonderful trailer with sleeping quarters but someone's really
let it sit...it will make the dream camper/horse hauler with a little
protective and cosmetic work (The inside pads, floor, and siding are all
immaculate, super-safe...it's just the outside looks like it's been through
a war zone with rust spots everywhere). Also color suggestions for covering
the dark maroon/yellow paint that's peeled off in sheets :-) I was thinking
black but will this really absorb heat badly enough to make a difference
even with the windows open?
I have my own ideas about this already but figure maybe someone out there
will know something I don't and feel like sharing :-)
If you make people think they're thinking they'll love you...if you really
make them *think* they'll hate you - Don Marquis