Yes. This is well within their discretion. However the less severe the charge, the quicker they should file a complaint or risk the case being dismissed. Generally for misdemeanor charges, the complaint should be filed and served within one year, longer for felonies. Retain a criminal defense attorney to protect your rights.
You were driving when you backed the car out of the parking space. During that time your BAC was above the legal limit. You will have a very difficult time fighting this one, but I would retain a criminal defense attorney to ensure your rights are adequately preserved.
You should immediately consult a personal injury attorney. Sounds like you have a disputed liability case that needs a professional touch. The other driver is probably just taking a swipe to see what sticks.
I agree it will be based on the contract/coverage language in your policy. However, depending on the facts of the case, you may have up to 2 years to file a personal injury claim. Obtain the policy documents, and then contact an attorney if you have questions regarding the contract language. If your injuries were caused by a third party, you will likely be able to recover the cost of medical treatment directly from them.
You can sue. The real question here is whether you would be successful in recovering money in your lawsuit. In order to prove a dental malpractice case, you have to show that the dentist/ orthodontist did or did not do something that they otherwise should have / should not have done. That is called a breach of the standard of care. Once you prove that a breach occurred, you must then show that you suffered a harm arising from this breach. The statute of limitations for these types of cases...