What is everything need to start a saltwater tank?

i already know how to start a freshwater tank for tropical fish and i know how to cycle it but how about for a saltwater tank? i am not going to start a saltwater tank right now but i want to know this for the future because hopefully in the future i get a 55 gallon tank or maybe even a 100 gallon tank and i want to make it a nice salwater tank with lots of coral and live rock in it like this: a href="http://www.fishometer.com/reef/images/Tank/100_4172.jpg" rel="nofollow"http://www.fishometer.com/reef/images/Ta…/a i am not sure what type of marine fish get along but i do know the names of many i like, like i would like to get some damsels and maybe some small gobies and some tang fish like achilles tang,yellow tank, blue tang, and also clown fish like the percula clownfish and black percula and im also not sure how big these fish get like i said i do not know much about saltwater tanks or fish i only know about freshwater tanks and i do know that saltwater tanks and fish require a higher ph like 8.4 so if i were to get a 55g tank what types of fish can i put in there and what about a 100 gallon tank? i am not getting this tank right now but id like to now this for the future so what is everything i need to know and what is everything i need?