gmod 11
The latest version of the Aether mod is for 1.0.0
Garry's Mod 10. When people refer to Garry's Mod 11, they mean the up-to-date Garry's Mod 10
The latest. Minecraft 1.0
Because you dont have Mod loader installed Google it to find out what it is
you have to downlaod a mod seach for a mod loader and the mod its self
Because you probably don't have mod-loader installed. Try reinstalling it.
It works fine on a vanilla version (no mods) so it probably means you have a mod for it so you will have to wait for the maker of the mod to update it to the latest version.
No. I use that mod and I don't have mod loader.
Go to www.garrysmod.org and download the latest version of DarkRP.
Just search in google 'Minecraft mod downloader'
Yes, however it may not be compatible with the latest version of S.T.A.L.K.E.R.: Clear Sky (version 1.5.10).
search it in the forums :)