I think the reason the SFB looses paint and rusts faster, is just as love2"Q" says, it's exposed to a higher heat, for longer periods of time. The paint on the main cooking chamber just isn't as close to the heat (at the top) as on the SFB, IMHO.
I haven't read the manual since I bought mine 2 years ago. I don't remember that part being in there. You will have to remove at least one of the grates to add some more fuel. However, I have yet to need to refuel my grill when i grilling, only when I'm smoking.
Peace, Love, and Vegetable Rights!
Eat Meat and Save the Plants!