If I buy a DIY f16, do I have to glue the fans in-place myself please?
In my experience with laptops, the fans have not been glued in place. The few I have replaced simply set in groves or had a screw on the housing.
From the videos I have seen of the Framework 16, the fans are part of the expansion Bay.
No, the fans are on the expansion bay module. You only need to install the expansion bay module and the fans will work.