Is my employee allowed to wait till the next pay week to pay me?

As indicated above, you are entitled to be paid regularly on your company's payday.

I quit my job while I was on medical leave, I would like to return the company laptop and access card with proof

Putting aside the issue of the company's property, it sounds like you may have a discrimination claim. I would consult with a local employment...

As indicated above, you may have a claim fort unemployment, but not for them firing you.

Can I sue my employer for one of the supervisors telling information that was private to another employee ?

While it may be personal, it involves work as it is between 2 employees. I do not think there is anything you could sue for.

What can I do?

You should contact an employment attorney as soon as possible as it sounds like you have an unpaid wage claim under state and federal law.

Can I get sued for breaching a contract?

To fully answer your question, an attorney would have to review the contract. I suggest you consult with an employment attorney to discuss further.

Doing work that's not in my job description

Are you in a union? If so, you should contact them as they should be able to help you. If not, you are an employee at will, and generally your...

Can they inform my coworkers I been taken off the schedule before I was informed ?

Unfortunately, this is not illegal.

It may depend on the type of work you do, among other facts. you should speak with an employment attorney to discuss your situation in more detail.

Fired for meeting up with coworkers after work?

Generally speaking unless you have a contract, you can be fired for any reason, so long as it is not a discriminatory one (due to your age, race,...