You are right and wrong.
1.) yup, it is auto-detected
2.) no, it doesn't increase speed... some special blendings (fade out effects, shadows) will be correct, if it can be used with your card
Perhaps I don't know what you mean By "Gpu ingame-menu"The gpu ingame-menu will show a little 'moon' symbol, if the extension can be used.
You are right and wrong.and for the moon-like things..it's auto-detect and intends to increase the fps a bit..5-10 fps if i'm right..