True. And like I said, an innocent party would have no problem helping out the police in the situation.
I agree. Remember that right after the shooting the police secured the TSBD and prevented everyone inside from leaving. And anyone outside from going in.
They were all questioned - except Oswald who had fled (in my opinion) earlier - and as far as I know all cooperated. Why wouldn't they?
There was no "reasonable suspicion" standard needed, as far as I know, to detain and question them since the police were involved in an emergency situation. Maybe the law has changed since then. I don't know anything about Texas laws on the matter and I'm very limited on my knowledge about US case law at that time.