Independent contractor v owner working in the business

Way too complex to try and review here. Find a good local business attorney.

Can I back out of real estate purchase agreement?

Completely depends on the contract terms.

My father is being sued by a lawyer for non payment of fees. The lawyer filed for a court judgement against my father.

California has law fee dispute arbitration requirements set by the bar. Call the bar and discuss if u can.

Do I have a case against my employer?

Medical issues can be discussed by your management when there are legitimate reasons.

Just to address one point you raised - defamation claims are very hard to prosecute and hardly ever worthwhile from a monetary standpoint. Even if...

Someone filed a fraudulent contract against me, written after work was done. He is attempting to supersede an oral contract.

Bring your evidence to court including any witnesses and documents. Good luck.

That's a question of what the underlying lease contract provided. You inherited just the unit. Check the terms of the contract.

Is it legal for employers to hire family memebers and pay them more than general employes?

Sure. Nothing illegal about doing that.

Is my F1 visa (not the status) still valid even after getting a H1B approval from USCIS?

No, since it was dependent on you continuing your studies.

Closing down a trust in Venice , California

Sure. You can file with court to object assuming you have good reason.