Well think of this...It may have been warm enough durring the day for it to fly. Why? Look at all the guys on the battlefield fighting. If it was -200, they couldn't move...

Actually, the standard TIE/ln's wings are structurally sound enough to support the weight of the craft, although it was designed specifically for specialized racks within Imperial hangers. There's no ladder system to let you down if you were to land on a surface and getting back up into the cockpit would be a major pain if you could get down. I don't know if the wings of other TIE variants could support their own weight, but I would imagine that the TIE Bomber wouldn't have any problems seeing as how it's the sturdiest of TIE fighter models (during the Civil War era).

The internal workings of the T-47's afterburners are greatly different from that of a starfighter. The X-wing and Y-wing squadrons stationed at Echo Base didn't need any modifications to operate successfully in such a harsh environment.

I believe all of the starfighters had repulsors (antigrav) so I doubt they would have had a problem flying near a planet's surface.  Besides, they, like the TIE Bombers, made many bombing runs on surface targets.