The gas isn't getting in the tank? Is it flowing out the top or leaking through the bottom? Never heard of this happening before...check for clogs in the fill tube I guess?
As far as the not starting, that might have to do with the lack of gas...
You should check your oil level to make sure you're not low. If you are, check for leaks. Chances are it's leaking from the valve cover gasket and oil filter housing amongst other places. Also check your coolant level to make sure you have enough. You will likely need to address the coolant issue ASAP so you don't blow your head gasket with an overheat. The coolant is likely leaking out of somewhere and a cooling system refresh seems like it's in your very near future.
I'm not sure what you have available to you to DIY stuff but it might be your best bet to save money. Also, don't ever take your car to the dealer for an oil change, you are getting ripped off.