gas tank question for 66 skylark

Im having a couple isses with fuel flow and the car is running out of fuel and falling on its face at higher rpm. The thing sat for a while and didnt have any problems at first, but its developed a couple gas leaks since I started driving it after I bought it this week. I fixed 3 fuel line leaks this weekend as well as two pin holes in the gas tank from what appears to be a sand blasting accident from the previous owner. But, Ive still got at least one leak left and at first I though that its sucking air through this hole, but this last leak confuses me now.

Ive got a couple questions about some things, but first I would like to know what the different lines coming out of the tank are for. There are two fuel lines in the center of the tank located near the bottom. the line on the right appears to be the line that supplies the pump with fuel. The other line located directly to the right and also in the center comes out only about four inches and is cut off and plugged at the end. What should this line be? Also, there is another line that appears to be coming out of the top of the tank on the passenger side of the tank. It is a rubber line comes out from the top of the tank, travels about 12 inches forward, and then mates to a steel line that bends upwards and goes in between the frame and inner fenderwell. I cannot tell where this line goes. Is this a return line or a vent or what? By the way, the steel line is broken and leaking fuel(as far as I can tell, this is the only fuel leak that remains). Im thinking that maybe this is the supply line. If thats the case, a leak in this line would explain why I am having fuel supply issues cause it would be sucking air, but it looks as if that line in the center is the one that supplys fuel to the pump, not the line on the passenger side. Does anybody know which line is what, and how is this tank vented and where should the vent be located? Thanks for any help guys.