Coffee Syrup

the old standard: Autocrat
for the modern "craft" type: Dave's (Quite good, but it's not the taste of a RI childhood. Discretion advised)

Chowdah (say it right, you heathen!)
Well, this depends on some things, like what his go-to place is. Since you mention Wah-wick, I'm going to go ahead and assume Iggy's. This is totally doable. Their's is of the thicker, more stew-like variety. The recipe they post is slightly off (don't try to tell me dill is basil, liars), but it'll get you close (use dill, but be careful, easy to use too much). Second paragraph describes making a roux, to which you always whisk liquid into, slowly, never the other way or you'll get a mess. If you have never made a roux, may want to practice a couple times - it's the foundation for many things and will add to your skill-set. Advice: Roux in one pan large enough for the whole batch, broth in the other, slowly whisk broth into roux as previously said. For the broth, add bacon or salt-pork to the pot along with the onions in the first step. The rest of the recipe is pretty accurate.

Clamcakes
Dude - ya nah gonna have chowder without balls of deep-fried dough with chunks of clams in 'em, ah ya? I'd just go with the other comment for that.

Lahb-stah
You sound like a good shit that knows better - you are correct.

Other things

You ever make Sloppy Joes? Make them a little spicier, add bell pepper and garlic, and serve in decent Torpedo Rolls. These are called Dynamites, but they are more a Woonsocket thing.

If you know someone up there that will overnight ship, pizza strips will travel just fine (and now we can all fight over who makes the best ones!)

The same might apply to frozen Stuffies from Dockside or Dave's Marketplace if shipped with dry ice...

Johnnycakes - it's basically a sweet, small, cornmeal pancake.

http://quahog.org has all sorts of nostalgic RI stuff to look through and get ideas.

I wouldn't try NY System / Weiners (WEEN-ahz) / Gaggers (GAH-gəhs) unless you can reliably get those little veal dogs... probably not worth it.

Donuts is donuts - can always just throw some in to round out a spread

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That's all I got off the top of my head... and I second the suggestion for RI Calamari, if you can get decently fresh squid. GOOD LUCK! You are doing a very nice thing here!