Use the brand you prefer. Some bags will say "for seed sowing" or something similar on them. Stay away from bags of soil that say weed-free as they may contain chemicals to prevent germination of weed seeds in that soil. Those chemicals will also prevent the germination of sown seeds. You may reuse potting soil or seed sowing mix after it has been sterilized. Put the sowing medium into a flat and dowse it thoroughly with boiling water. Allow to cool to room temperature before sowing your seeds.

I don't think they use dirt but rather sphagnum moss. Any vine should grow thru it as long as the sphagnum moss is kept moist. Look here for info on how to rebuild http://www.hort.cornell.edu/livingsculpture/pdf/sphagnum_topiary.pdf

I'd skip sand (as we typically think of sand) and wouldn't even consider garden soil/top soil for a potted plant because the nature of the soil's drainage characteristics change dramatically between garden and pot. A garden soil that might accurately be said to have excellent drainage/aeration in the garden is very, very likely to compact severely (which significantly reduces air porosity) and retain water excessively when moved from garden to container. Even if we consider using garden soil or topsoil as a minor fraction of a container medium, there are much better alternatives. Al

Give it a test run. Pot#1. Best potting soil you can buy Pot#2. Permanent mix or Sandy loam with no composted tree parts See what happens after a year. Which plants did better. They both start out great but as the potting soil ages the oxygen content decreases so root health declines. I watched this happen every year to me. I tried the experiment in almost all sand. Plants grow with no problems. They don't need dead tree and they don't want dead tree around their roots. Dead tree is a cheap material to sell and light to ship. The growers that plant in ground up composted wood know their plants are going to have problems months later. They tell the nursery or big box store to get rid of them before then. watering becomes tricky then. To help keep the mix from rotting too fast you need to let the mix almost dry out before you water again. This stresses the plant. Plants like cool, even moisture and oxygen at the root zone. Some of the 5 gallon shrubs will die a year or two later after planting. The roots continue to decline in the rotting mix. Adding ground up tree amendment to the hole only makes it worse. Sometimes you can carefully shake the grower's tree compost off the roots and replace it with mineral soil and plants will be fine after a few weeks in the shade adjusting. I know this is controversial. The nurseries sell the mix and schools teach these practices but it is not what the plants want. ( a NASA guy told us this when they researched what plants want for the space station ) They want to be in a mineral soil with the organic matter breaking down on top. A study was done of undisturbed natural soils in a variety of locations. The organic matter found in the soil was all living. Roots, fungi, bacteria, worms, etc. Not dead tree bark branches and leaves. That stuff is on the top of the soil and fungal networks break it down so the plants can use it.