I posted a similar question some time ago and there were some example images posted which did clarify a little but not that well...
Shall try to dig it up with the search.
In the meantime I'll try to answer them myself:
1) glow amount is how much glow (not the strength --> less glow is only glow on part closest to the sun, much glow is glow all over it)
2) strength is how strong the glow is
3) don't know
4) don't know
5) Fake internal scattering is what it says: with this setting the inner side of the clouds is lit up. Lower this value and the inner side of the cloud-shapes will darken, increasing contrasts. If you have very dark cloud colors and increase the fake internal scattering you can end up with white clouds with darker edges. (a question posted over a year ago)
6) Also what it says: how strong the enviro light affects the cloud. Simply put: the higher the value the brighter the cloud.
7) Goes along with the previous setting and determines the color of the enviroment light affecting the cloud. You could use a blu-ish or yellow-ish tint to simulate either atmospheric depth or sun's glow when sun's at lower angle.
These are all my interpretations of course and they seem to work fine to some extent.
I also would like to see some staff jump in to describe the 3rd and 4th setting and also to correct me.
However, we might have to wait for the official TG2 manual when the final is being released, some time
Martin