photogirl -- I'm a healthcare provider from a previous life dealing with LOTS of PI clients... here's my take (and sorry, really as I would expect your healthcare providers to be able to offer this clarification or any info. you'd obtain from the book that M3 is offering):
I too would not recommend meeting in person, likely the adjustor is going to offer to write you a check for your "inconvenience" and then have you sign a form (in order to receive said check) which is called a Hold Harmless agreement that says you can never try to claim benefits, payment, injuries etc... in the future, that one check will make things done.
Depending on the Third party claims adjustor and how full their case load or desk is, some will call weekly, some monthly but likely they are recording you on any given conversation so even a harmless, "So, how are you feeling today?" and if you're having a particularly good day and say something to the effect of "Not too bad", they are going to look to use that against you later to say that by that date you should have been fine and no further trmt needed. What I used to advise my patients (while letting them know that my advise was NOT legal counsel) was to just tell the Third Party adjustor, "Hey, I'm focusing on getting better and I'LL CALL YOU!" (when you're ready to talk settlement).
As to the records release to access your medical records, again I'd suggest to my clients to go ahead and sign it if you want, but somewhere in the language of said document to write in, * or whatever, that you authorize records to be released from the DATE OF INJURY forward ONLY b/c really that's all they are entitled to, nothing else.
And ultimately, yes you are obligated to deal with the Third Party Adjustor to settle your claim unless you hire an Atty and they will deal with everything for you including any communication or issues with your own PIP which I tell you I've seen plenty of those, too! Your PIP will deal with them to be reimbursed and made whole (which is the whole idea of PIP and why your rates won't go up b/c you weren't at fault), but they won't necessarily be looking out for you beyond that. If you are interested in the help of an atty I can suggest a GREAT one, but your health care providers can as well and the Atty's I worked with always offered a complimentary consultation to any of my clients to just chat about the case, ask questions etc... and then decide if you did or didn't want to hire them. I bet your chiro's have a few they could recommend that would do the same.
Anyway, hope that helps. And GOOD LUCK!!