Eastham it is for vacation, need final suggestions

[Jim in CT]

Based in part on the awesome feedback here, we rented a house in Eastham from June 16 - 23. The house is right on the bay, above the beach, with steps leading down to the beach. House is on Martha Ave in Eastham, if anyone knows that area.

Anyway, I welcome any and all suggestions for a good family vacation. My kids are 6, 3, and 1, all boys. Obviously we'll spend a lot of time at the beach below the house. Here's where I need help...

Cool things for the kids? I know there is a fish hatchery where they can feed fish somewhere near Sandwich, I know that seals gather at Chatham fish pier for eating by-catch tossed overboard.

What other fun things can we do?

Is it worth driving to First Encounter Beach, or should we stay at the house?

Suggestions for rainy days (movies, kids' museums, etc)?

Kid-friendly charter captains in the area?

How about a lobster cruise, where we watch the capt pull up the traps? I've seen guys offer that, I think the older 2 would love it.

Restaurants for lunch/dinner? We love seafood, and we prefer casual (a clam shack with picnic tables) to ritzy places. Where to go for lobster? Where to go for fresh clams? Any must-hit restaurants?

How are the whale watches in Providence?

Might I see some fish at the beach where we're staying? Worth fishing at night? Eels, or artificials with a sand eel teaser?

Thanks again. We have never been to the Cape, and we are psyched...