The lines on each side of the top of the fuel tank are for the heater. They typically leak where the mounting brackets are connected. I have removed the short, leaking section of one of mine and replaced it with a 3" piece of heater hose.
Yes, those are for the heater. They are soft brass, and easily crushed when reinstalling the hoses to them. If they are leaking at the hose connection in the engine bay, you can often pull the hoses off and gently bend the pipes back to round, and then install new OEM hoses and clamps, (if yours are tired) and it will solve the leak. I believe the pipes run the length of the car, so they're not all that easy to replace, and are pretty expensive.
I managed to fix mine by bying one of the small sanding drums. I just took off the sand paper drum and then inserted the rubber drum inside the brass pipe. I then turned the nut and the rubber expanded perfectly forcing the brass pipe to become round again.
It was not extremely easy, but it paid off by not leaking anymore