In your area broccoli ( asumming a cultivar that gives sideshoots) should produce most of the summer. Each successive flush of side shoots will be smaller. When the size is no longer suitable for you, pull the plants.

Yes, the plant will continue to make smaller and smaller side shoots that will quickly bolt in hot summer weather. They are edible if you pick them quickly before they flower, but many find it not worth the bother.

Don't know if there is a way to trim the Broccoli so it produces bigger shoots when the weather gets cool. With mine, usually either my dog eats the plant or the cabbage maggots eat the roots, but you can keep the Broccoli plant going well into winter. Broccoli and Kale will survive in the snow but once you get temps in the teens the plants are pretty much mush in Ohio. Maryland is more mild thou.