1) & 2)
Where to even start American history is so rich with examples of racial and capitalist development in how America was discovered at the very beginning of capitalism as a system. It would not be hard to put America into context the need for capitalists to generate wealth to fuel their home industries and put into place racist, violent systems to divide the working class. Capital Vol 1 (Part VIII) has a section describing the basis for colonization on the early history of America.
>The discovery of gold and silver in America, the extirpation, enslavement and entombment in mines of the aboriginal population, the beginning of the conquest and looting of the East Indies, the turning of Africa into a warren for the commercial hunting of black-skins, signalised the rosy dawn of the era of capitalist production. These idyllic proceedings are the chief momenta of primitive accumulation. On their heels treads the commercial war of the European nations, with the globe for a theatre. It begins with the revolt of the Netherlands from Spain, assumes giant dimensions in England’s Anti-Jacobin War, and is still going on in the opium wars against China, &c. ... These methods depend in part on brute force, e.g., the colonial system. But, they all employ the power of the state, the concentrated and organized force of society, to hasten, hot-house fashion, the process of transformation of the feudal mode of production into the capitalist mode, and to shorten the transition. Force is the midwife of every old society pregnant with a new one. It is itself an economic power.
You most likely know about this but I would recommend A People's History of the United States by Howard Zinn.
-The American Political Tradition And the Men Who Made it by Richard Hofstadter
-An Indigenous Peoples' History of the United States by Roxanne Dunbar-Ortiz
-The Road Not Taken by Lerone Bennett ( https://msuweb.montclair.edu/~furrg/essays/bennettroad.html
) Not a book and is a short one.
>What makes this all the more mournful is that it didn't have to happen that way. There was another road -- but that road wasn't taken. In the beginning, as we have seen, there was no race problem in America. The race problem in America was a deliberate invention of men who systematically separated blacks and whites in order to make money. This was, as Kenneth Stampp so cogently observed, a deliberate choice among several alternatives. ... Back there, before Jim Crow, before the invention of the Negro or the white man or the words and concepts to describe them, the Colonial population consisted largely of a great mass of white and black bondsmen, who occupied roughly the same economic category and were treated with equal contempt by the lords of the plantations and legislatures. Curiously unconcerned about their color, these people worked together and relaxed together. They had essentially the same interests, the same aspirations, arid the same grievances. They conspired together and waged a common struggle against their common enemy -- the big planter apparatus and a social system that legalized terror against black and white bondsmen.
-The Many-Headed Hydra: Sailors, Slaves, Commoners, and the Hidden History of the Revolutionary Atlantic by Peter Linebaugh and Marcus Rediker
>the authors show how ordinary working people led dozens of rebellions on both sides of the North Atlantic. The rulers of the day called the multiethnic rebels a ‘hydra’ and brutally suppressed their risings, yet some of their ideas fueled the age of revolution.
-An Economic Interpretation of the Constitution of the United States by Charles Beard
3) As someone who went to high school in the same region as you're working in and recently graduted, I would not hesitate to assign reading short passages because it opened my eyes to so many different interpretations and it made me a better reader. All of the material earlier is what I can remember from being in a US history class taught by an anti-racist, (openly) Marxist. He was so bold he assigned reading the Communist Manifesto as homework assignment and to either affirm/deny the predictions made in the Manifesto in the modern era which gave an out for the students who disagreed with the reading. The point, maybe you can't be so ambitious in your school as to give the Manifesto, is that it's definitely possible to create a historical anti-racist, working class, multi-racial narrative in the school system. Good luck ! Hope you follow up on your results