Y-DNA Part 1 -- My head is spinning!

A while ago, brother Chris had his DNA analyzed, to find the Y-DNA history in our family, that goes back through Grandpa Bill Ortman's line. (When I had mine done, it was mt-DNA, the line going back through Grandma Walli.) All this stuff is very complex and (at my age :) difficult to understand, but I've been puzzling through it. First, the basic stuff we learned.
Source: familytreedna.com
So much as it was with my chart, which started with "Mitochondrial Eve" in East Africa, this one starts with "Adam" (also in East Africa -- they had to be in the same neighborhood, right?), and much as mine broke up into smaller groups with letters representing groups that went off in different directions, so does this one. Our path (through Grandpa Bill) went from Adam following the A, B, F paths, then K, then P, and finally to R, third from the bottom, in the brown part of the chart. We are R-M269, as a matter of fact, which is easier to remember than U4b1a1a1 on Gra…
Source: familytreedna.com
So much as it was with my chart, which started with "Mitochondrial Eve" in East Africa, this one starts with "Adam" (also in East Africa -- they had to be in the same neighborhood, right?), and much as mine broke up into smaller groups with letters representing groups that went off in different directions, so does this one. Our path (through Grandpa Bill) went from Adam following the A, B, F paths, then K, then P, and finally to R, third from the bottom, in the brown part of the chart. We are R-M269, as a matter of fact, which is easier to remember than U4b1a1a1 on Gra…