Not on the facts you describe in your post.
This answer does not constitue legal advice, nor does it creat an attorney/client relationship. If you are seeking legal advice upon which you intend to rely, you should hire competent cousel familiar with this area of the law in your locale.
Probably not, but you should contact a local real estate attorney for a consultation. You should also notify your homeowner's insurance carrier and the title company that you used during the purchase and ask them to provide you with coverage and a defense.
If you have been sued, make sure you get an attorney so you don't put yourself at risk.
Yes, he might have a prescrptive easement, but so does everyone else in the world, since that easement was used by the general public. He does not have the right to exclude others from use of the easement, as the public use was open, adverse, notorious and hostile to the landowner(s) whose property the easement traversed. So what's his point in making a claim? It's meaningless.
This answer is provided under the Avvo.com “Terms and Conditions of Use” (“ToU”), particularly ¶9 which states that any information provided is not intended as legal advice or to create an attorney-client relationship between you and me or any other attorney. Such information is intended for general informational purposes only and should be used only as a starting point for addressing your legal issues. In particular, my answers and those of others are not a substitute for an in-person or telephone consultation with an attorney licensed to practice in your jurisdiction about your specific legal issue, and you should not rely solely upon Legal Information you obtain from this website or other resources which may be linked to an answer for informational purposes. You understand that questions and answers or other postings to the Site are not confidential and are not subject to attorney-client privilege. The full Avvo ToU are set forth at http://www.avvo.com/support/terms . In addition, while similar legal principles often apply in many states, I am only licensed to practice in the State of New York and Federal Courts. Any general information I provide about non-New York laws should be checked with an attorney licensed to practice in your State. Lastly, New York State Court rules (22 NYCRR Part 1200, Rule 7.1) also require me to inform you that my answers and attorney profile posted on the Avvo.com site may be considered "attorney advertising" and that "prior results do not guarantee a similar outcome".