There is a Portsmouth, Rhode Island. I'm assuming that's what the OP meant. Just be aware that driving back and forth to Providence during rush hour times is ...
Downtown. Probably best around Faneuil Hall.
Where are you picking up the motorhome?
Marriott Long Wharf, Marriott Custom House, Marriott Copley Place.
You didn't answer the question - Harvard University or the Town of Harvard? They are not close to each other.
It won't be less than 15 minutes, but 20 minutes is possible. Taxi fare will be around $30-35 per cab, which includes the toll, airport fee and tip.
What is the whale trail?
It's usually a very small parade,
I don't believe the Freedom Trail sites will be impacted by the Veteran's Day holiday. Bear in mind that churches along the trail do have scheduled Sunday serv...
That's a much better (and safer!) plan.