The '97 Geo Metro (Base, LSi or XFi) does not have a fuel light.
Were can I buy a throttle cable for a 97 geo metro
front of the engine
It depends on the size of your engine.
It is 17mm.
I know mine is under the hood and I have a 97 geo metro so you may want to start there.
Most auto parts stores have wiring diagrams for a 97 Geo Metro. This includes wiring diagrams for the brake light, head lights, and much more.