John "Braunche" and the Branch's

I recently discovered I'm descended a good deal from the Branch line. The Branch line in mention came to Henrico Virginia and is documented quite well.

I've been dreaming of going back into the Medieval era, and I've finnally worked my way back into it. It was during this I came across a man by the name of "John Braunche" who was born in 1400 (or about) and died in 1488 and assumingly came from Abingdon. It was at one point I stumbled upon a site that claims to have documentation of individuals who served in the English Ranks. One of these men listed, who shared the same name, had enlisted in 1415.

If this was the same man he would have obviously been quite young, however, my question is would this have been possible for a man so young? I'd imagine enlistment wouldn't have been so specific as it is today, and is there any way of finding them to be the same man? Or different men?

http://www.forces-war-records.co.uk/Medieval/Record?recordId=11632&recordDb=medieval_muster_rollhttp://www.forces-war-records.co.uk/Medieval/Record?recordId=11632&recordDb=medieval_muster_roll

My second question concerns the Branch line in a broader sense. Surfing through the message boards there was some excited talk that men such as Christopher Branch (1602-1681, and is a grandson of the previously mentioned John Braunche) are related to figures such as Thomas Jefferson and more related to the medieval section here, King Henry I. These discussions were not too recent (2008 I think) and I was curious as to what may have been discovered since then as it appeared to suddenly explode and suddenly drop off in terms of discussion...