1. Regarding the passenger who was laying down during takeoff, were they laying across all 3 seats? It's possible he/she did this after the FAs did their last walk through.
2. Seat belt on with only light turbulence - we don't know the whole situation. Often the pilots get info that leads them to believe turbulence is ahead. Sometimes you get an over;y-conservative pilot. I would say neither is the normal.
3. Maybe one of the FA's can chime in, what is the procedure if you can't safely prepare the cabin for landing - meaning if the the FAs need to remain seated for their safety until landing.