K&N's website does not mention the 4.6 at all, just the 5.4. I would guess this has been mentioned before, but I cannot find any mention in the threads I have checked.
Second question: how much of a factor is it that it could suck in hot air from the engine compartment?
I am primarily trying to improve gas mileage. (that's what I tell the wife.)

 

Yes, the same kit will fit.I believe it is kit #2514, I have it in my Expy 4.6l.

 

Thanks!