Flushing without dropping the pan is stupid no matter what they tell you. The only way to change the filter is to drop the pan. If the filter gets plugged or dirty it stops doing its job and restricts flow which will reduce line pressure then your transmission can start to slip.
The bands probably don't need to be adjusted every time but I do on mine, it depends on how it gets used. The first adjustment (after break in) on a new truck is most important.