Because of its finer consistency, topping asphalt gives a smoother finished product, as well as a tighter surface which resists water penetration. This will extend the life of the asphalt. Bracken Paving will look at your situation and help you decide what type of asphalt would be suitable for you. Compaction is important to the appearance and longevity of asphalt. With better compaction there is less chance of water penetration through the surface, thus avoiding cracks.
Depth is the most important aspect to the actual laying of the asphalt.
As with basestone, the right amount of asphalt will vary from job to job. Obviously this is not necessary for a home driveway.