I hope this message finds you well, present circumstances excluded. First of all, this is a bad situation and with bad situations, good outcomes can be a relative phrase. I have been dealing with criminal law matters for over 10 years and have seen situations like the one you are in numerous times. With that being the case, I will answer your questions in the order in which they were presented.
1) What are my general rights when I go into the station today for questioning?
You don't have to go in for questioning about the situation unless or until a warrant is issued for your arrest. Even then, you do not have to answer any questions. However, if you do not go in, the police can legally hold your vehicle as evidence and prevent you from having access. If you go in, you don't have to answer their questions and can take the 5th, but they frankly may further incriminate you if the police want to take that approach. Since you are not guilty of any wrongdoing in the matter, I would advise you to go there and answer their questions. If you can afford an attorney to go with you, then I would advise that as well just to be on the safe side.
2) Can anyone provide any law, rulings, or advice that will help me leave with a release for my vehicle, today, or soon?
The only reason the police can keep your vehicle is if they claim it to be evidence in an on-going criminal investigation. If you go in and voluntarily speak with them and nothing in that conversation leads them to believe you were involved in the criminal activity, then the will have to release the vehicle to you.
3) Anything in California law that could help me avoid having to pay the tow fees?
Unfortunately, unless the vehicle was stolen from you, you will owe the impound and towing fees associated with the confiscation of the vehicle. Your legal remedy to recover the amount lost will be a civil remedy against the individual that you loaned the vehicle to when the criminal event occurred.
4) What kinds of questions might they ask me?
In all likelihood their questions will center around what you knew about this person when you loaned the car (did you have a reasonable suspicion or knowledge a crime would be committed) and what involvement you had (if any) in the criminal activity. Obviously, just be honest.
5) Is there any type of limit as to the time length they're allowed to question me?
Unfortunately no, but you have the ability to leave anytime you want unless and until the arrest you. Moreover, they should take reasonable steps to make sure you are comfortable (water, bathroom breaks, etc.).
6) If they are trying to find out information on this individual (I have since learned I really didn't know anything about him.. sigh...), what tactics might they use to trick me into thinking I have to make statements that could accidentally get ME in trouble or get HIM in worse trouble?
They will ask you leading questions that attempt to put works in your mouth. They will ask questions in declaratory fashion like, "since you knew him to be a criminal, what did you allow him access to your car?" Your response is that you did not know he was a criminal. Be careful to listen to their questions very carefully and do not allow them to make assumptions on your part of put words in your mouth.
After the questioning, you need to write a memo to yourself that describes in great detail what the questions were and what your responses were to those questions. This way, if there is a second round of questioning, you can use the notes or memo to make sure you give the same answers again.
You have a great attitude and should keep it up throughout. You have done nothing wrong and our system, while flawed, is pretty good and letting the innocent walk. You have nothing to fear.
Let me know if you have any additional questions or comments.
Best wishes going forward.