#1, #2, #3: Seachem products, either the reefbuilder/buffer/calcium or the Aquavitro line, are easily the most forgiving method in the business to keep a reef in great shape.
http://www.garf.org/bulletproofreef/bulletproof.asp">GARF's Bullet Proof Reef calculator</a> is a great starting point for how much of Seachem's products to use on your reef as well as a great method that's easy for beginners.
#4 - Everything but the fish, though they would use calcium (I assume) for bone structure, so technically, just about everything but stuff like flatworms and sea slugs.
#5 - All animals are intollerant of certain forms of dosing calcium if not administered propperly. Too much kalkwasser will kill just about anything in the tank.
#6a: Start with something that comes with complete, detailed directions and is designed to be used as a system. That is, if you decide on two-part, use one company's two-part as well as their other suggested methods of dosing additional additives (such as magnesium). If you go with Seachem, use either all the necessary Aquavitro products or the older builder/buffer/calcium ones. Mixing and matching is not for the beginner.
#6b: Test often when begining a new dosing regimen until you're sure the amounts you're using are getting the numbers you want.
#6c: What works for one person may not work as well for you or at all. Every tank is different.
