For your dash lights it could be something as inexpensive and easy fix yourself as a bad igntion switch or a bit more expensive and less easy to diy, your alternator going out, luckily the alternator is easy to diagnose if you have a multimeter.
The p0455 code and hard to gas up could either be a bad purge valve, shutoff valve or EVAP cannister.
I also seem to recall some fill tubes that could possibly be slipped or tweaked that would cause the gas problem but I am not sure which years that this might affect. I am not sure if this would cause throw a code either.
Approximate prices not for the items, not including labor, to fix the above issues are:
Ignition switch: $20-25
purge or shutoff valve: $100
EVAP cannister: $150 - 275 depending on which cannister your year uses. The more expensive one actually comes has an opening for the purge valve and includes it along with what I think was a vent tube while the less expensive one does not include either nor fittings to accept them, it is just the cannister with different tube attachment points. Don't ask me how I know...
Changing the cannister and/or valves is a easy operation to do. You just need to remove the passenger wheel and wheel well liner and you will see them to the rear of the wheel well. Once you get the wheel off, the only other tools you will need are a flat tip, phillips and a rachet and socket (i forget which size) for the RNR of the rest. I think it took me around a 2-3 hrs to change my cannister.