The men appear to be deliberating a document.. perhaps the Declaration of Independence or the Constitution. Given the British flags in the background, I would assume the DoI.

They're doing that to break away from England. 

Lexington/Concord

British troops organized

American troops in disarray and not unified

Multiple casualties on American side, none (depicted) on British side

I noticed a lot of the "s"s are written as "f"s. I wonder if this is an example of how language has changed over time.

The American/British army lines are solid in Brooklyn but dotted in Queens and Manhattan. Perhaps the dotted line represents retreat?

Washington is the tallest (and highest) person in the painting. The only item taller than him is the American flag – this shows the power of Washington, but national pride above all. 

The left side of the painting (where Washington is headed) is lighter than the right side (where Washington is coming from). However, the clouds still appear gloomy on the left side. This may indicate that Washington is heading into "calmer territory" of the war, but danger is imminent.

We think this piece is trying to depict how the Americans have become more powerful as the war went on. At the Battle of Lexington the colonists were disorganized and surprised, but here they appear unified and proud. Additionally, the British appear confused (based off the surprised looks exchanged by many in the left half of the piece); this may signify that the British were shocked to lose this battle and are realizing the war may not as easy as they had hoped.

Group: Sam, Sam, Sam, and Sam

The British were surrounded by enemy troops in all directions

The Americans had positioned themselves in a way that they can see if Britain tried to escape via water as well

If I was Washington, I would start the attack on the British at night with a combined French-American effort and have American ships in the river in case the British attempt to leave that way