I have a Gen6 but no pre-plumbed tank. This is a pump anti-seize feature. However, on mine it only runs if there has been no pump activity in the last 24hrs. I do not use the heat pump for DHW, so there would be long periods in the summer where the pump was not used and could potentially seize.
I do not believe so. I contacted Samsung support last year about this and the frost protection system that does a similar thing. If the outside temperature falls below a certain value, it then periodically turns the primary pump(s) on (every 15mins, I seem to remember) to prevent the outside unit from freezing. I have glycol in that part of the system so that is unnecessary, but according to UK Samsung support, you can’t turn it off. Of course, a firmware upgrade may have changed this in the interim.