1) The patch panel is where you land your cabling that comes from the locations in the home. The connections on this board are 1 to 1, meaning that each punch down is connected to one port. So every port you want to make active you will need to connect, via a patch cord, to a router or switch. If your router has four ports that means you can connect for location. If you want more than that you can for example get a 8 port switch. A switch is like a router in that it that it takes single data signal and splits it into multiple signal, but a switch does not assign IP addresses. A router does assign IP addresses, the router is the main controller and the switch is just a expansion of the router. You connect the router to the switch by simply plugging a patch cable from one to the other. Any of the outgoing ports from the router can be used to make connection to the switch, on the switch you should plug into the WAN or LAN port. If you do not have enough ports available for the amount of location you have then you need to get a bigger switch with more ports.
2)There is no recommended placement of components inside the enclosure. The only recommendation is however you arrange them try to keep the cabling in mind. You will need room to make all your connection so leave space between components to do so.
3) This is the order things should be connected MODEM>ROUTER>SWITCH
4)T568A is for residential applications, T568B is for commercial applications. So if you are installing this in your home use T568A.