As long as you're not currently on probation (it sounds like you're not), you can purchase a firearm. Additionally, you must be 21 years old.
For more information, check out: http://www.atf.gov/firearms/faq/
The US Marshals house federal inmates in county jails pending sentencing. Whether your husband was sentenced for a federal or state crime, he will be transferred from county jail to prison to serve his sentence.
The other attorneys are correct in saying that there is no set fee. If you cannot afford to hire an attorney, you should ask if there is a victim advocate in your area who could be there to support you in court. Check out:
Based on the facts you gave, it sounds like you have a defensible case. I recommend you speak with some attorneys in your area as soon as possible. Once you retain an attorney, he or she can speak with the prosecutor assigned to your case and hopefully convince them to not go forward with a formal charge.
Best of luck!
It sounds like you have an excellent reason to challenge the stop. Be sure to hire a good attorney who will file a motion to suppress the illegal stop on Fourth Amendment grounds.
You should contact the Clerk of Court to see if you can possibly get a new court date. Chances are they will not reset it though and you will need to elect to take the school at this point to avoid points on your driving record. FYI, you would have better luck getting a new court date if you hired an attorney.
Below, is a link to the Clerk's Office. Good luck!