3-Make certain they have photos, names, addresses, and phone numbers of customers from three years ago and if they cannot supply them then don't hire. Here is a link that might be useful: Propagating Perennials

All three. The topsoil will hold the base material in place, you will still need to edge the walkway but the soil will hold whatever this is in place too. You could do it the other way round but this would involve concrete to hold up the edgers and this is the way most commercial jobs are done. Topsoil first is the cheapest way.

ants look for moisture so perhaps those with problems have a cracked paver or a crack in concrete. Even if hairline crack, ants will go to it. Important that ground is level and compacted prior to installation to mitigate risk of cracks and related problems, ie ants

As pointed out above, permeable paving has nothing to do with inhibiting weed growth; it is used to reduce runoff. In many cases, it also requires a much more costly preparation. There are a number of silica/polymeric sand mixtures that can be used to reduce weed growth. Of course, as new material blows in from above, you'll still get weed growth. If it's manmade, it needs maintenance. Here is a link that might be useful: Permeable Paving This post was edited by worthy on Fri, May 31, 13 at 17:56