Forced overtime at minimum wage?

Do any of these actions violate the terms of ancollective bargaining agreemnt or employment contract? is our treatment due to some form of legally actionable dsicrimination (i.e. because of you race, religion, nationa origin, disability, age, etc.)? if not, then as an "at will" worker your employer can set the conditions of your employment much as it sees fit. Accordingly, they can give a raise or not and decide when to give it, as well as schedule you to work whatever days it deems necessary and pay you at a "punishment rate". That is so long as they comply with overtime laws and you earn at least your state's minimum wage. 

Yes, your boss can do this, as long as you are still paid at least minimum wage, and you get overtime (assuming that you are hourly) when you work more than 40 hours in a week. Your employer:
1) Has complete control over you schedue: you can be forced to work weekends;
2) Can have different rates for you for different shifts, days, or work;
3) Can give you a lower rate as a punishment--or for any reason at all; and
4) Is not obligated to give you a raise at all, and so can withhold it for punishment or for any other reason.
Note: the above assumes you do not have still-in-effect [that is, unexpired] written employment contract which sets your wage or guaranteed you a raise; if you do, the employer must honor its terms.
Essentially, without a written employment contract, your hours, days, and pay are completely under your employer's control, unfortunately.