The two sided bits are for drills. Not impact drivers. And the bit holder (left lower center) is a slide extension. It helps to guide screws into place.
yes, 1/4 inch diameter hex sided bits.
They are 6 sided bits. They are not round. They have a 1/4 inch shank.
I like the Ryobi drills, with lithium batteries. Make sure you get bits like these with the grove at the bottom.
Yes, these are for impact drivers and are a standard size.