If We Know That Two Lineages Split 20 Million Years

If we know that two lineages split 20 million years ago, and we know the degree of molecular difference between contemporary representatives of each, we can estimate

A) their phylogenetic relationship.
B) the amount of time that has elapsed since other pairs of related species converged.
C) how far back in the past the two lineages shared a common ancestor.
D) the rate of change that produced that degree of difference.
E) how long it will take for the groups to completely speciate.