Some of what you posted is normal, and some is outside of normal. The doctor's note is standard. From what I have observed, this is a position that gets a lot of call-ins. The call center is likely staffed to meet certain criteria that possibly have high penalties if missed. Someone calling in sick may put those penalties in jeopardy.
The amount of break and lunch time varies by state. You could Google your state to see what you are legally required to get. If they are not in compliance, I would talk to someone at the temp agency about the conditions and see if they have any leverage to influence change. Sometimes, new front-line managers try things like eliminating breaks without realizing the legal consequences, and this may need to be escalated to upper management or HR. It sounds to me like you have inexperienced management, and that always makes me wonder if their managers realize what is going on.
It is in the company's best interest to make the employees' job as pleasant as possible, even in a call center environment. This is an entry level job, but it is still expensive to train a replacement and get them up to speed.