Hmmm... you know, when you put it like that, that's true. But it wouldn't really matter with Kakashi, since I believe the flames will automatically erupt on him, since he'll be the target. It'll be Kakashi flailing that'll make the fire spread - the embers being tossed around and whatnot.
My assumption on Madara is that he did his time/space jumping thing. But that's just my guess.
As for the fore field and the fire... I guess it would. It's like a magical flame that will not go out! Of course, I don't know how long those fore fields can last for, so there's always that problem.