Well, for restaurants there is a wonderful local chain called:

Legal Sea Foods. There's one in Boston, one in Cambridge, and there are several in the 'burbs, all good. A famous waterfront fish eatery with no name so you have to refer to it as 'Noname'.
A brand new chain of very good places called "A Guy Named Joe"
You may or may not care that the American Revolution began here. There are several wonderful and informative places re: the local history:

The Freedom Trail - In my experience this requires walking, and you specified not much, but you should know it exists, and there may be a way to navigate it by the 'T'. But it includes Faneuil Hall, Paul Revere's house, and a few other sites. Like most of the people who live here, I did my sight-seeing in the days I didn't live here!

Lexington Square - Where was fired the first shot in the American Revolution 19 April 1775. This is worth going to to say you were there, it is now encompassed by a busy but not unattractive New England town center (Lexington) however it is on the way to:

Concord Bridge - "By the rude bridge which arcs the flood, their banners to April's gales unfurled, here the embattled farmers stood, and fired the shot heard round the world. - don't check that it was from memory and my eyes teared up.

Where the Yanks took the first British casualties. A beautifully kept up site. While in Concord you should go right next door and visit The Old Manse, which has historical, literary, and religious ties and a garden once tended by Henry David Thoreau. And you are a few driving minutes from Walden Pond.

You can't get to Lexington and Concord via the T but if you rent a car they are relatively easy to find.

Boston area people are among the most agressive drivers in the nation, and navigating the roads in the city is a trial to be approached with both patience and a bit of aggression your own self. There's a Boston Driver's handbook subtitled "Wild in the Streets". This goes by way of saying that you shouldn't really rent a car unless there is no other way.

This is a big college town, there are many many colleges and universities here, there are folk dance groups (often allied to universities) and you can probably find most of them on the web. The Unitarian Church is very big in this part of the country and has long sponsored a great deal of folk music activities. This info may be out over the web, I know that a suburban church calls their folk assemblies "circle of friends". (And yes, the SOF is big here, too!)

Go to www.boston.com and that gets you in with the Calendar published by the Boston Globe on Thursdays. The long-time once counterculture Phoenix may be online, haven't checked.

Feel free to IM me for ideas. I lived here for a long time before I moved to Alaska, and I'm back in the area for a term, although probably not up to June.