My Ford expedition back end is hang low is alternator bad

You may want to give up on a 23 year old ford and up grade before putting a bunch of money into it .

Sounds like you need a good shop to check this out. Yes it will be expensive so you may want to do one thing at a time or sell it as is where is.

Most likely the compressor for the level ride system is running excessively because the system is leaking. That's probably what's killing the battery. Unless the battery is old and no longer holding a charge. For the fuel smell you need to have the fuel system checked out. It's probably leaking or there's a problem with the EVAP system. Is the check engine light or service engine soon light on? If so visit your local auto parts store and have them scan the computer for trouble codes. You'll probably get an EVAP code that will need to be fixed by a reputable shop. Hope that helps! Jim