You do not owe money for a car if it has been repossessed, so your wages can't be garnished for that reason.
READ your contract.
YES.
No In Texas your wages can be garnished by the IRS or Child Support only
in most states, yes.
Yes, the two issues have nothing to do with each other.
Yes.
Yes, wages can be garnished in Illinois.
Yes, if there was a deficiency balance owing after the car was sold at auction. Your creditor would have to sue you and obtain judgment in order to garnish your wages.
Yes.
http://www.nlsa.us/public/consumer/cn1_collection_procedures.htm looks like you have problems
yes