It is difficult to answer this question without knowing the nature of the potential claim. If your house is your homestead, then the answer is most likely no because of the Florida homestead exemption. For instance, if a construction lien was placed on your home, a contractor could potentially foreclose its lien against your home. In addition, you should consult with your accountant regarding the advantages and disadvantages to paying off your mortgage.
In general, you should be able to recover the money you paid to an unlicensed contractor that failed to properly complete the work. If you plan on pursuing this matter, you should do so sooner rather than later.
If you have a written lease agreement with your roommate, that agreement would control disputes you have regarding your tenancy. If the agreement doesn't address utilities but you have an oral agreement to pay half of the utilities, you should keep track of everything you pay in case a dispute arises in the future. You may also want to put your agreement to pay the monthly amount owed plus $50 in writing, assuming your roommate would agree to do so. Based on the limited set of facts you've...
You may be able to stop the transfer of the vehicle if the repair shop doesn't have a valid lien on the vehicle or if they failed to give you proper notice of their intent to enforce the lien. You need to take action immediately to protect your rights.