Can we bring cameras?

Yes you can, I think it's pretty much encouraged.

Are dogs allowed

Yes, you'll be disappointed if you don't bring a camera.

YES cameras!

Absolutely, cameras are allowed, Id actually recommend taking your camera because you'll probably want to take a picture of one of their awesome flowers.

Do you have to wear a mask

I would refer to the website. There are specific rules if dealing with a commercial photographer then with a personal use of a camera https://longwoodgardens.org/visit/frequently-asked-questions#Photography

Definitely yes

Definitely bring a camera.

Yes