Hendersonracing, the shrooms looks great, but one caution, if they take over, you wont be able to keep SPS alive for very long, I got rid of 99% of my mushrooms. When it comes to Chemical warfare in a reef tank the shrooms will win out every time.
as for adjusting your calcium, do what lvreefer sugested, he is correct. Goto the chemistry forum and learn from Randy home he is awsome.
I've found that its easier to bring up alk because you can add something like baking soda to bring it up, but if your alk is high and to lower it, all you can do is wait for your corals to use it up.
As for buying frags, the member sales are good, places like reefermadnes is great also. Start with some thing easy like montipora, and fast growing green slimer and things like that and once you are able to make those corals thrive then your tank is ready for new stuff.