The mounting brackets on the passenger seat are rusted and the flooring in it's vicinity is discolored because of it, some moisture from outside (snow) has slowly spread the discoloration and I'm worrying if this is going to rust the floor panel or rather worse, if it's already rusting and spreading. How can I contain this without damaging the flooring? I have the proper de-rusting materials and tools. Thanks in regards.

If I can I will add a photo in this thread for clarification.

 

Throw the pic up just since its easy. Also, rust isn't "contagious". If the carpet is just stained, but stays dry nowadays, new rust doesn't form from rust dust. Rust is formed by moisture, electrolytes, and dissimilar materials. Oh wait that's corrosion.... but you get my drift. Best bet is to take the seat out, then pull back the carpet and take a look. Might as well start the prevention process now instead of the repair process later.

 

Surface rust can be cleaned up in most cases via scraping, sanding, grinding or whatever you have to get it back to bare metal. Take care of any pits in the metal as well. It should be primed with a self etching primer, and painted over. If the rust has eaten thru, then that part needs cut out and the metal replaced. Check the entire floor as one pinhole can easily become a 6" hole or more once you start poking at it.