Best use of fridge/freezer

G’day all – first attempt so don’t be too harsh!! we bought a Siemens fridge freezer some time ago but only used the fridge (i know!!). Recently we have discovered how useful the freezer is for meat and fish. I have a number of very basic questions:

1. How full should the freezer drawers be? in other words what is the optimum clearance from the food to the cooling element?

2. What type of pen/marker should be used to mark the individual packages?

3. In the ‘fridge. when we have bagged items such as pre-packed salad, condensation often appears inside the bag. This causes the veg to dampen and go off. What causes this and how can we avoid it?

4. Occasionally there is a build up of “snow” in both the freezer and the ‘fridge. What does this signify and what action should we take when it occurs?

Many thanks for any advice you can provide!