This site may be helpful in answering some of your questions, Joshua20. Its an evidence based resource that may be a little more reliable than most ".com" sites out there and its for military athletes. Click on the dietary supplements tab; might take some searching, but you can search specific supplements and ingredients to determine positive effects, negative effects, safety issues, etc. You may have to search by individual ingredient.
http://hprc-online.org/
Milon