You really need to determine what type of saltwater tank you want. Fish only, fish only with live rock or reef setup. This will guide you on how much live rock you need.
http://www.fishlore.com/saltwater_aquarium_types.htm and
http://www.fishlore.com/live_rock.htm.
As for the protein skimmer, I have a Coralife Super Skimmer 65 for my 60 gallon bow-front. It's a hang-on the tank (H.O.T) or sump type of skimmer. Break-in time is 24 hours. After that it just starts working. The picture is of the skimmer on it's forth day ( 1 day break-in 3 days normal use ).
Do some research ... From AquaC skimmers (great) to SeaClone skimmers (not so great) and everything in between.