Here are the choices you have as far as a stainless exhaust is concerned:
-The Banditmania one
-A factory stainless one.
Both were not available in the states and were available in Europe. You can find them from time to time but shipping is the biggest kick in the nuts, probably more than the exhaust is worth (depending of course on how much you want to spend). Ebay is your friend there.
You can do what I do for testing the steel and that's just tapping it with the handle of the a screwdriver and listening. You can poke as well but be sure you can repair the damage if you go through. Concentrate more on the lower bends where water would collect (the pipes will more likely rust from the inside out) and if it sounds consistent, you're done.
The majority of the rust happens from the front wheel spitting up rocks, etc dinking the paint off the header. The tubing the factory uses is quite thick, usually why there is a significant weight savings to be had going to an equally non-existent performance system (they use thinner tube steel). That being said, unless the bike has sat outside and collected alot of water or done short trips to not burn it off, it should be fine.
My plan of attack at some point this year will be to demount the exhaust, chemically strip the existing layers of paint, use phosphoric acid to neutralize the rust and paint with VHT ceramic exhaust paint. You could also have the pipes coated with a ceramic powedercoat or even jet-hotted but I personally don't want to spend that much.
Be prepared to at least touch up the paint once a year at the lowest bend by the front tire as well as the first bend coming from the head. Those locations take the most abuse.
You can make the stock exhaust perform a little bit better by modding the header as well. Search around, I did the mods and posted results, which to me were all positive.
Welcome to little bike ownership. The most tedious 400cc you'll ever love.