Help! Help! Help! Gas Leak!!!

My car (95 Chevy Lumina) has been acting kinda funny lately... a few days ago it wouldn't start properly (it was shaking and sounded like a train... someone thought it might have been a loose spark plug... but they all checked out). After we added some fuel cleaner stuff, it seemed to clear up.

But now I have found a small gas (I think!) leak! I pulled out this morning and there was a puddle under the car back where the gas tank sits. After watching it for a while, I noticed a small drip (so it definitely is leaking).

I know ABSOLUTELY NOTHING about cars!!! Can anybody tell me how much it may cost (ballpark) to get either the lines patched or replaced? Might the tank be leaking? Is it safe to drive for half a day until i can get it to a garage?

Can anybody tell me how much it may cost (ballpark) to get either the lines patched or replaced? Might the tank be leaking? Is it safe to drive for half a day until i can get it to a garage?
It is NOT safe to drive!!! Have it towed to a mechanic. What is your life and the lives of others worth? (Think flaming fireball here)
Cost depends on that has gone wrong. If its a loose hose clamp, bad filler hose, or the o-ring for the sender, its about $60, maybe less, installed. Cost goes up from there, depending on what has failed.