first ill post how i think it is currently:

1)
3 gs/br is what they should get currently
plus 1-2 cm kill assuming sdi
assuming 100% turnout so a fraction of that, probably 70% turnout used to be normal maybe a bit higher now

2)
with only 15 people id expect maybe 20 second cm kill, in bigger war it was lower down to about 5 seconds at minimum

3)
id say a kill is bad if its slower than a minute, and good at about 30 seconds, to go under that you need to waste resources which is a choice

4)
550 is considered normal at 235 hits, they dont tend to be more than that without walling

5)
in pure turns you max out at 18.666:1 ratio for gs, but that can go higher with DH's and lower with bio's
most wallers wind up facing BR with bio and need to sit higher on pop unless the nw difference is huge then returns drop earlier to 10, but that still makes it around about 8:1 turn efficiency

6)
choices here would be FS advantage/tempo, cd/gs superiority, inability to wall large chem rush, land drop meta, walling variability swinging wars, size of wars getting too small, land drop meta