Can you teach me more about lug bolts & related tire tools?

Can you teach me more about lug bolts & related tire tools on this vehicle
whose tires I rotated today and which I plan on rotating every 4K miles (6K
km).

First question is what is the practical difference between these three 21mm
(13/16ths) "sockets" for the lug bolts on the car I was working on today?
http://wetakepic.com/images/2018/02/17/socket_ends.jpg
1. The standard lug wrench (green) has 6 points, each at a sharp angle.
2. The impact socket (black) has 6 points, each at a semicircular angle.
3. The standard socket (chrome) has 12 points, each at a sharp angle.

Second question, are these "cut marks" on a lug nut normal?
http://wetakepic.com/images/2018/02/17/dented_nuts.jpg
I always use deep sockets, which fit over the whole nut, so I know I didn't
make these marks - but what did make the marks? Are they factory original?
If so, why?

Third question is related to this combination pictu
http://wetakepic.com/images/2018/02/17/torquewrench.jpg
Where this question is a combination question of:
a. Why is the green 21mm "lug wrench" so very short compared to all others?
b. What's the practical difference, if any, with respect to torquing lug
bolts to 85 foot pounds (115 N-m), between the two types of torque wrenches
shown?
c. Does anyone even use that bottom-most "auger style" ratchet bar for fast
removal anymore? (I don't have power bolt-removal tools so that's why I use
it.)
And, the most important question, for torquing lug nuts, is
d. Does the torque change depending on the length of the socket extension
bar?

Fourth question is more of an observation than a question, where I combed
the tires for rocks and nails, as I always do when I rotate the tires every
4K miles, when I saw this tiny little steel dot embedded in the rubber in
each of the front tires.
http://wetakepic.com/images/2018/02/17/splinter1.jpg

That tiny dot turned out to be this funny-shaped steel sliver, pointy side
was pointing into the tire in both front tires.
http://wetakepic.com/images/2018/02/17/splinter2.jpg

The question is whether these embedded rocks and splinters, of which I
always find between 50 and 100 in each tire (mostly tiny pebbles and bits
of glass stuck in the tiny sipes of the tire tread) would eventually fall
out as the rubber wears (negating the need to periodically pick them out at
each tire rotation)?
http://wetakepic.com/images/2018/02/17/splinter3.jpg

In summary, I ask these basic questions simply to learn more about how to
better rotate tires every 4K miles (6.5K km).