Ground support: The number of aircraft Strategic Bombing is halved. (Does this mean all aircraft are halved including fighters or just bombers?)
Since desert hex has NE for Snow and Mud turns, would the air units using a desert city for basing purposes still be affected by the snow and mud modifiers per the terrain chart or are the modifiers ignored?
No, they are not affected.
Fortress: Has -3(in other posts, it now means +3 for defender) on chart for combat. But the rules state the fort has an inherent 2 strength(and it has a 2 printed on the fort counter). So, does that mean a fort is essentially a 5 strength unit on the map for defense?
It's two. Grrrrrrr... sorry about that.
Also, in other posts, it was stated that terrain is cummulative. So, if a 2 strength fort (plus +3 per chart) is in a city spot on a clear turn (+1 per chart), would give it a total 6 for strength, correct?
Yes, the bonuses can stack up... Forts do cost for stacking (1 corps)
On movement, assume the fort movement terrain overrides the terrain it is sitting on, correct?.