You have many good questions which I am sure a number of VolleyFamilies will have, so please allow me to break them out as to answer:
1. NCAA rules are changing for college coaches, but one of the basic rules is not being able to make contact with a PSA (prospective student-athlete) on site during a competition and the definition of "during a competition" is the length of a tournament. So, I would not have your daughter go say thank you - She can always do that via email that night.
2. But, since she is now a senior, you are allowed to go say thank you. This is a nice gesture, if the coach has made a special or solo trip to see your PSA. But, keep it short and sweet, to allow the coach to get back to doing their job - If the coach wants to chat, they will make that obvious.
3. It is normal for coaches to not talk or interact with VolleyFamilies at tournaments - This is because your PSA was a junior and any interaction by NCAA (again rules had changes for DII, so I am making a broad statement) coaches at a tournament would be a violation.
4. I would error on the side of 'not bothering them' - A quick hello or thanks, from now on is more than enough. Away from the gym, via phone, email or official/unofficial visits is where dialog and information is best exchanged.
5. College coaches are adept at seeing and evaluating what they want in a short time segment and really don't want to 'recruit' a family in the gym. It is better and more comfortable for all involved to have this recruiting process occur at the school or home of the family (a reference to the almost extinct Home Visit). It does not surprise me that the coach watched, left and then sent an email.
6. I would say that the junior college coach is casually interested in your daughter as a recruit - If she is truly the best player on the team, then he is obligated to give her the award and I am sure he would be very happy to have her on the team. But, if he has not talked to her, then he is not interested in recruiting her actively.
Good luck and keep working through the process. I would encourage you to take a look at Inside College Volleyball, where I have written extensively on contact rules. Also, you may wish to get in the NCSA Athletic Recruiting network because NCSA does a great job education and with the new contact rules coming our way in August, it is valuable information.