both
The name coming first is the primary owner.
yes
Yes
Most states will allow you to register a car in one name even if two names are on the title. Of course, the registration has to be in one of the names on the title.
If the car is paid in full and two names are on the title with an "or" (ie. Jane Doe or John Doe) then either of these people can get a new title without the other person's name on it. If the title uses "and" (Jane Doe AND John Doe) then one of the people would have to sign over ownership to the other.
If there are two names on the title it cannot be seized for the debts of one owner. You should consult with an attorney.
Both people own the car. If the names on the title show John Doe "and" Jane Doe, the title must be signed by both John and Jane before it can be sold. If it shows John Doe "or" Jane Doe, only one signature is required to be able to sell it.
No, if your name is one of the two on the title. That makes the car as much your property as it is theirs. If you intentionally deprive them of the use of the car by hiding or destroying it, then it becomes a civil matter - not criminal.
Yes. How many names are on the title and/or the loan means absolutely nothing... so long as there is a lien on that vehicle, that lienholder is the sole lawful owner of that vehicle, and can repossess it as recourse for delinquent payments.
Yes they can. Both of their names can be on the title!
The owner(s) is the person whose name(s) is on the title.
How a car may be sold with two names on the title depends on the local law where you live. In the United States, property law varies from state to state. On some questions it is possible to walk 10 feet and the correct answer changes from yes to no.