The space required for the hedge depends on which plants you want. Thuja might need a bit less, but if you want flowering shrubs, they can sometimes grow up to 5m high and 3-4m wide. Our planting strip itself is a bit narrow because we chose the strip first and then the plants. It is curved, with a width of 1.2m to 0.5m, the narrow spots now mostly have smaller shrubs.
There was already a fence everywhere towards the neighbors, but we made the one towards the street ourselves. That definitely depends on personal taste.
Theoretically, you can also do without stones between the lawn and the shrub bed. Under the shrubs, a weed barrier fabric and bark mulch should keep the weeds somewhat under control if you don't want lawn under the shrubs.