Can I be sued by an illegal immigrants?

I agree..report it to your insurance..a foreign person can sue you...not sure how you know he is "illegal"

Can I take a margin from my users on-line transactions ?

This sounds fine..I agree 5% sounds low.

I do not see any legal recourse here and you will have to deal with this through whatever work channel that exists. The law does not stop people...

I will be borrowing funds from my parents to purchase a car for my business and will repay it as if it were a bank loan.

You should also speak to your accountant to make sure you are meeting all of the IRS requirements to deduct the interest. Also, your parents will...

What should i do

You can sit down with a personal injury lawyer...most good firms have VERY high success rates but that is because they only take a small percentage...

Can a cease and desist order be issued against me by a service provider who got my money, did not complete the work?

I agree.

Can I have auto dealer arrested for keeping my deposit?

I agree..this is not a criminal matter..it is a civil matter so all you can do is sue. Given the facts, it is not clear you would win..it would...

I need advice on deportation, and the best way to become a U.S. citizen.

He should get a lawyer as he will only have one shot at this.

How do I find out if my decease mother had any bank accounts

I agree..find out who managed the estate.

How do I dissolve an L.L.C. in South Carolina when my business partner is being uncooperative with completing an inventory, etc?

A lawyer would have to look at your operating agreement to answer this. Perhaps set up a consult with a lawyer in your state.