Depends on where it is leaking.
14:1 compression
4 1/2 litres
Coolant is all pretty much the same from manufacturer to manufacturer. Check your owner's manual to find out the right mixture for your Sunfire
You can compare prices online at any of the big box parts store's websites.
Pin point your problem. A "gas leak" on a obd2 computer can be hundreds of mechanical references. An ASE certified technition will most likely be your bet to locate your leak, after the leak is located you will know the cost.
i have no idia
no
I'd try to find one in a junk yard. I wouldn't expect to pay more than about $10 or so.
by bum
It depends on where the leak is and what is causing the leak.
Barry Bonds made alot of money... he made 14,989,65 per year
4.5 quarts