Squirtle Community Day Sunday July 8
https://twitter.com/PokemonGoApp/status/1009165876657115136
Answers
Probably the first CD I don't care about so much (Edit: Just remembered Mareep, that was almost as uninteresting). 1/4th egg distance is hard to take advantage of in just 3 hours and Blastoise isn't going to be meta relevant no matter how good Hydro Cannon is. I'll probably focus on grinding tasks as community days do make that extremely easy.
I think there's a trick in the wording here.
"Eggs put in incubators during the event will hatch four times as fast!" Not 'you get 4x walking distance during the event.'
So if I read this right, you can put an egg in during the event, not walk one step during the event, and whatever you put in during the event hatches at 1/4 distance, whenever you walk it. Makes the short time of the event less important, it's like the evolve window for a special move, once you evolve, you get it - once you put the egg into the incubator, you get the bonus distance.