The first thing with marine tanks to know is.. BUY THE BIGGEST AND BEST YOU CAN AFFORD..
Save yourself the money latter on, Once you get into the hobby.. nothing is bigeough.. bright eough.. ect..
29 gallon is good.. with marine tanks they can be a hand full to maintain, So the larger the tank you go the easier it is to maintian.. i started with a 29 gallon tank a year ago.. i now i have a 29 gallon, 45 gallon, 90 gallon and a 72 gallon.. all marine tanks.. and im looking to have a custom 300 gallon made soon..
as for live rock.. YES.. You want 1 - 1.5 pounds of live rock per gallon of water.. this is what will filter your marine tank.. you do now want any Mechanical filtration on a marine tank execpt for a skimmer, and you want to get the largest and strongest skimmer you can afford.. if you have a 20 gallon now, Buy one good for up to 200 gallons, Becouse one day you will have atleast a 120 gallon tank with most likly a 60 gallon sump.. so you are going to need it.. so dont waste your money on a smaller one now when you are just going to buy one later.
as for CAL, Yes depending on what you are keeping, there is plently of Calcium in "Saltmix" what is used to make saltwater.. but if you are keeping much harder corals.. Like SPS pr clams.. witch eat up all the Calcium they can then you need to dose more into the system to compensate for what they are using up..
Ideally all you need to start your tank.. is .. a Tank, Salt mix, Heater, Sality tester, water current.. nad test kits.. ( Calcium, ALK, PH, nitrates, nitrites,ammonias, phosphates) are all kits i bought when i started my first tank.
as for the maintance.. depending on your bioload.. if you have the correct amount of live rock.. and a resonble bioload.. then you can do somthing like 5% water change every other weekend.. some like myself have too much in there tanks.. and i need to do 20% every weekend..