To create an Airport, I would use either gmax (free with FSX Deluxe and FSX Gold) or FS Design Studio 3.5 (from Abacus for $US50) OR you can also use 3DS Max too, if you can afford it.

For me, FSDS is easiest because you put the coordinates of the objects (buildings) when exporting them to the BGL file. I've never even tried creating scenery objects with gmax, so I don't know what is involved there. Both have their advantages and disadvantages, although I think that gmax is the harder, but more flexible of the two. I bought the gmax Bible and the gmax Handbook to learn how to do things with gmax, but I still need a lot of help from the FS development forums.

Here is a link to the Sim Outhouse Design - Gmax Tutorials Forum: http://www.sim-outhouse.com/sohforums/showthread.php?93-Gmax-Tutorials, which will be a great help to what you want to do.

Sorry that I can't help you with the fuel burn or takeoff landing speeds for the B-52.