Failed google search - few questions about astronomy.

I think I'm becoming a xxx
I tried to find over 1.5 hour on Google a few facts, but either
Google become worse, or I'm not as effective in finding this on
Google as I'm when trying to find something about hacking, warez, and
weapons.

So basically:
1. reflectivity of various gases. How hight must be wavelength to
rebound from athmosphere for each gas.
2. absorbtion coeficient. Or better what wavelengths could go
throught various gasses without restriction.
3. Rain. You know there should be some zone on planet to allow a
rain. (possibly) or at least decrease planet's outgassing.
Requirement for that zone and of course some ideas how to count it
for various ranges and star temperatures.

BTW what would happen to planet if it would be in the middle of two
red dwarfs? Could it survive it and have double day?