I would highly recommend getting a qualified attorney in these matters to mitigate the possible jail time and penalties. There's a lot at stake so getting one or not shouldn't even be a question. Good luck.
As you may already know, you are protected by the Eighth Amendment to receive necessary medical care while imprisoned. I would contact your existing attorney and ask him/her for any referrals to an attorney specializing in these matters if he/she is unable to take this on. If you do not have an attorney, I would either find an expert attorney through the Avvo filtered searches or contact my local ACLU. Best of luck.
Estate planning attorneys would handle wills and trusts and they typically charge an hourly fee in reviewing an existing will or a trust. This fee would also cover any revision of an existing will or a trust.
You do not mention if there is marijuana already in the car. If marijuana is found after you are pulled over, you'll likely be arrested and you would need to retain a criminal defense attorney to get you off. You may not get arrested if the car is searched and you can show the registration that the car is not in your name.