I haven't googled your links yet, but will when I'm done with this. Have you tried census records, church records, tax records, court records? Sounds like you have the deeds under control - now, you just take a step back & see where he was living prior to buying that $750 house!

Will books are especially rich, and the New England Genealogical Society has a TON of records!
I hear you about the same name - there has been a John & a William in literally every generation of my family thus far! It become sheer torture when we found a completely parallel family in the same area - two each of John McCulloughs who married Elizabeths, with a brother William for three generations! We pretty much had to do both family trees to keep them straight as to who belonged to whom!!