1. Indiana employers are required to pay time and a half whenever an employee works more than 40 hours in a week. The Fair Labor Standards Act does not define the terms "full time" or "part time," but also requires employers to pay time and a half after 40 hours in a single week. Because overtime is calculated on a weekly basis, employees are not entitled to overtime for staying late on a single day unless required by contract. So, if she worked more than 40 hours in any previous week for which she did not get paid overtime, then she should file a claim for back wages.
2. Under the Affordable Care Act, a full time work week is 30 hours or more and a part time work week is anything less than 30 hours. Employers with 50 or more full time employees under this definition must offer an affordable health insurance option to their full time employees or risk owing an Employer Shared Responsibility Payment to the IRS. This provision only goes into effect if an employee of the company receives a premium tax credit from the IRS to help that employee pay for health insurance.
Also, the ACA treats any combination of full and part time employees working at least 1500 hours to be the equivalent of 50 full time employees. For example, a company with 20 employees working 30 hours a week and 45 employees working 20 hours a week would still reach the 1500 hour full time equivalent threshold and be required to offer health insurance.
3. As to other benefits such as paid sick days and holidays, those are determined by company policy and the employee handbook. If she meets the criteria set forth therein, then she is entitled to those benefits. They cannot deny them based on race, age, gender, etc. Otherwise she could file a discrimination case or breach of contract case, if no discrimination applies. The employee handbook is treated by the courts as a type of contract that both the employee and employer have to abide by.