skiwillgee,

your thoughts about such a Dyson sphere are very well thought, most of the problems you describe lead ultimately to the conclusion that such constructions can't exist even the most optimistic futurists are mostly sure about that,  just thinking about the need of material!

Let me quote from one of my favourite books, 'Entering space - Creating a spacefaring Civilization' from Dr. Robert Zubrin what he tells about Dyson spheres:

For example, if such a "Dyson sphere" were built in our solar system the shell radius would be about 1 AU (astronomical unit, 150 mio km, earth-sun distance) and the inner surface would therefore have an area of 283 billion square kilometers. This is about 553 million times the surface of the  Earth. If such spheres existed, they would radiate strongly in the infrared. Ergo, the search fpr advanced extraterrestial civilizations might be conducted by looking for such spheres. To date, no Dyson spheres have been observed - I'm not suprised. Dyson spheres are impractical. The 1-AU sphere described in the previos paragraph, if given a shell just 1meter thick, would require the mass from 260 disassembled Earths to build (and 1 meter is much too thin for it to hold together).
[...]
Moreover, while advertising a trmendous nominal surface area, most of the inner surface would really be useless for habitation because, except near the equator, where the rotation of the sphere could suplly outward-pointing centrifugal force, the gravity vector almost everywhere on its surface would point in rather invonvenient directions. As a result, there could be no air any significant distance from the equator. Terraforming the rest of the sphere would be impossible, since no matter how many air you made, it would all either flow to the equator or flow to the sun.

End of quote

:) Hope this helped a bit...

However, it's still a nice element of scifi stories ;)

Benny / lordgoron