You can see Ooni Pro's blueprint here. We recommend a sturdy table that is capable of holding weights upwards from 30kg (66lbs). Wooden picnic tables are perfect. Most surfaces are suitable, including wood or stone. We wouldn't recommend using glass or plastic.
Ooni Pro should be placed away from structures and buildings and performs best when set up in a space sheltered from wind. If you are cooking on a windy day, position your Ooni Pro so that the air enters through the rear to encourage airflow.