Re the seat sliding:
I was told by an instructor many (many) years ago that if this happened, (as it may in Cessnas) to throw the controls forward, even put your feet on the controls, until you were able to slide the seat forward by natural means..
Not a natural cause of action to release the controls, but always in the back of your mind in a Cessna. However, if you are aware of the issue. you always check the seat is secure in your pre-checks so hopefully this will never be an issue.
I think the problem may be the lack of information transferred between generations. Unfortunately most new pilots are unaware of the lessons learnt prior to their licence... especially when operating old airframes/engines unless they have had similar experienced instructors..
I am not saying the seat was an issue in this event, but all aviators should be aware of the implications, and the response I was taught may or may not suit the situation. I am just putting it out there...