Forced to work for 6 months - prior to being offered full time employment though my offer letter was "at will" through an agency

What is the question ? I don't see an issue.

This "phantom income" is indeed taxable I the eye of the irs. There are a few ways around it, including you giving a promissory note and working...

Is it legal for my employer to give me the option to voluntarily quit my job or fire me if I am enlisting in the navy?

Absolutely unacceptable. At a minimum I would let them know they are violating the law. Depending on what you want to achieve, you could also...

Do I have an employment case? I'm I supposed to be paid? I'm a medical volunteer EMT at a NFL stadium that doesn't get paid.

I'm confused... What is the question ?

In California when you apply to work at a job can it be considered discriminatory for an employer

You really at not providing much by way of facts. But a business does not have to serve you, nor employ you, unless those reasons are...

What kind of lawyer can help me obtain approval to buy, transport and sell 3" Chlorine tablets in the US? Sodium Hypochlorite.

Regulatory or transactional business attorney should be able to help.

How do I get legal assistance to help me review a revocable family trust if was closed six months ago?

Much more than can be addressed in this forum. Find a local attorney.

Experience Letter when resigning from a Employer

No. There is no law requiring an employer ton issue such letter.

Immigration

I would find a local immigration attorney for advice. There isn't enough information.

One more question about immigration and green card renew application

Use legal aid help. USCIS won't help you complete forms.