Gas gage

Check the simple stuff first. Most gas gauge sending units are grounded with a ground wire to metal right by the tank. Corrosion causes a bad ground over time, and the gauge is nonfunctional. The sending unit might also be bad, as well as the gauge itself, but a bad ground is often the problem, and it's a simple fix.

Actually, all the are not working, none of the gage/needle works on the dash at all

All the gages, /headlights/flashers/are working. Except the right lights/front, rear. And the right flasher goes a little bit faster when turn on

The burned out bulb on the front causes the light on the rear to flash faster. Also a bad ground on your gas gauge sending unit can cause the actual gauge in the dash to stop working. This is common on older vehicles where road salt, etc. is used to clear the roads. Otherwise, locate a factory manual and start troubleshooting.