You can see what juries have awarded by going to a law library which may have research materials that show the verdict amounts by the type of case or injury. Additionally, you can research this at verdictsearch.com
Without an attorney, the insurance company will offer you less than with an attorney. I would expect you'll get an offer of $1,500 to $2,000. What an attorney would ask for will depend on other factors besides the medical bills, e.g. the amount of vehicle damage, whether there was medical insurance, what the medical or insurance liens are, etc.
If your son was hurt, you should hire a personal injury lawyer to handle your son's claim against the driver's insurance company. You don't need to file a lawsuit right away and incur all the costs of a lawsuit.
Insurance companies routinely claim that the medical bills are excessive, especially if there isn't much car damage. Your attorney may be able to get the insurance company to pay more or to get the medical providers to accept less.
Yes, they can take you to small claims court. But if she's being paid for all of the damages by the two insurance companies, she won't have any damages to sue you for. If she's still having to pay all or some of her deductible, then she can sue you for that. She may not win, but she can still sue you and try to win.
Most medical malpractice attorneys take cases on contingency. You can use the Avvo Find a Lawyer tool to look for some or do a Google search for medical malpractice attorneys in your area. You might look for them also in nearby larger cities as well. Good luck.
You could hire an attorney to send the homeowner a letter by certified mail asking them for their homeowners insurance information. If phrased correctly, such a letter that they have to sign for, which indicates that the information needs to be provided within 10 days of the letter, will in many cases do the trick.