5 points
Every cribbage player knows this.
5 points
6 potential pairs, but you can only ever submit two pairs at a time without reusing any cards.
2 points
Looks like n of a kind results in (n^2-n)/2 pairs. (Which is the same as the sum of 1…(n-1))
5 of a kind would be 10 pairs. 6 of a kind would be 15, etc