How does a ready gold token work? Do you get both energy and fulfill a power requirement when it is rested and killed?

No, a Gold gear token only adds Power — not Energy — when you exhaust and kill it.

A Gold gear token is defined in Rule 184.5 as having the ability: [Reaction][>] Kill this, [E]: [Add] [A]. That breaks down as: exhaust it + kill it → add 1 Universal Power to your Rune Pool. It does not generate Energy, and it does not fulfill any Energy requirement.

You can activate this ability during an Open State (Main Phase), or during the Pay Costs step of playing a card or ability (thanks to the Reaction tag — see Rule 429.3). Once you pay the cost (exhaust + kill the token), the Power is added immediately, and you can spend it on any Power cost of any domain.

The only exception is if you also control Chem-Baroness Renata with her legend ability active (within 3 points of Victory Score), in which case Gold adds both 1 Energy and 1 Power per FAQ #9476.