Which Substrate?

Currently I am using normal black quartz sand. Is it true that it is not so good to use quartz sand for planted tanks, as the sharp edges of the quartz sand may cut the roots of the plants and cause restriction to healthy growth of the plant?

1) ADA soil and sea chem Flourite, Flourite red, oynx gravel or other brands. Which do you use?

2) There are serveral types ada soil, which type to use? (i.e Aqua soil amazonia, africiana, malaya)

3) Do you guys use those normal type or powder form, or combine?

4) Do we mixed those ada soil with other normal substrate or purely ada?

5) At least how many inches from the tank bed?

Thank you.

http://www.seachem.com/products/gravels.html
http://www.adgshop.com/Substrate_System_s/1.htm