About William Mead, there were several in MD and PA, but these, I think are the same or closely related:
In 1681, William Mead signed a petition in Cecil County, MD.
In 1693, William Mead was on a tax list in Chester County PA.
(Chester and Cecil are neighboring counties.)
On March 7, 1725/26, William Mead's son, also named William, was mentioned in the will of Martha Darke of Falls Township, Bucks County, PA. Martha's niece, Ellen Worrell, married William Mead, the younger.
The first William would have been at least 21, I assume, in 1681, possibly older, so it's possible he was the grandfather of John.
Everything I know about Richard Abrahall/Abrell is in previous posts on this forum.