Yes, unless you have an employment contract or local law specifies otherwise (which it usually does not). Employment is typically at-will, meaning that you may be terminated at any time for any or no reason.
YES
Yes they can tell you that you have to come in.
It depends on the employer's sick leave policies.
He can certainly fire everyone involved and hire new people who are less confrontational.
can a employer contact you while you are covered by a sick note
It can be used to call an ambulance if someone is sick or injured, the fire brigade in case of fire, or police if you are being threatened.
No the employer will have to give you sick leave once a year .
Generally 'laws' do not cover policy regarding employer/employee contact. Some employers require a daily call-in from employees, some require that employees be available for phone consultation when they are off sick. If you feel that your employer's requirements are onerous, you should contact your state employment department for assistance.
He can for the day that you claimed to be sick.
Sick pay is unregulated. It is a gift from some employers, and the rules are whatever the employer says.
It depends on your employer but typically it will be paid as straight-pay and not overtime pay. Straight-pay meaning your normal hour wage.
You suspension is as long as your employer says. You cannot change it to sick leave, even if sick.