Some told me it was a dog park, is that true?

Hi there. It's called the Bark Park. More info on their Yelp Page here, including the free registration required to visit (there's also reg. forms at the gate). East Longmeadow Bark Park Yelp link: https://yelp.to/qTKq/lA1wituRKQ Facebook link: https://www.facebook.com/East-Longmeadow-Bark-Park-158810510810823/

Yes

There is a dog park but you have to register your dog with the town before they'll let you use it.

Yes, check it out sometime