Excellent questions!  Thanks for posting them so others can also learn.

Here is a link to the applicable statute: http://legislature.maine.gov/legis/statutes/23/title23sec3101.html

Paragraph 2 says, "Call of meeting. When 4 or more parcels of land are benefited by a private road, private way or bridge as an easement or by fee ownership of the private road, private way or bridge, the owners of any 3 or more of the parcels, as long as at least 3 of the parcels are owned by different persons, may make written application to a notary public to call a meeting. The notary may issue a warrant or similar written notice setting forth the time, place and purpose of the meeting. Copies of the warrant or similar written notice must be mailed by means of the United States Postal Service to the owners of all the parcels benefited by the private road, private way or bridge at the addresses set forth in the municipal tax records at least 30 days before the date of the meeting. The notice must inform the owners of the planned meeting's agenda and specify all items to be voted on, including, but not limited to, all proposed budget items or amendments that will determine the amount of money to be paid by each owner pursuant to subsection 5. Subsequent meetings may be called in the same manner or by a commissioner or board appointed at a previous meeting pursuant to subsection 5."

So the notary's role is to issue the warrant. Then copies of the warrant must be mailed - but it doesn't specify by whom.

If you go to the Resources page of the MARA website and scroll down to MARA Conference 2020 Handout Materials, you will find a sample Application to Notary Public, and a sample Warrant 1st Meeting. The Application needs three signatures, but they do not need a Notary. The Warrant needs the signature of the Notary.

Once you have elected your officers at the first meeting, those officers are supposed "to be sworn," but no one seems to know exactly what that vague statement means. According to the attorneys who spoke at our conference, it's probably archaic language held over from the original statutes which date back to the 1800's, and it's unlikely any Court would deem your road association invalid if your officers failed to be sworn. But they said to be sure, it would probably be a good idea to have a notary swear the officers in and document it. If it's more convenient for them each to go to a separate notary, I don't see anything prohibiting that, except perhaps the difficulty of persuading the notary to do something they are not familiar with. I asked the Notary at our bank if she would swear me in, and she looked befuddled and said, "We don't do that."