The DC One Million continuity is separate from the current New 52 continuity, meaning that "Golden Superman" - known as Superman Prime - is not considered part of the same continuity. Even when it was introduced, DC One Million was considered a "possible" future of the DC universe and not completely canon.
As for his powers & abilities, Superman Prime is essentially Superman to the Nth degree. He has all of the abilities normally associated with Superman plus the following:
- The ability to alter objects at the molecular/atomic level
- The ability to share a fraction of his power with anyone from his bloodline
- The ability to see light in the infrared spectrum
- Possesses a Green Lantern ring (possibly the last one)
- Immortality due to his centuries of absorbing solar energy
Also, it's important to note that - due to his extensive years of soaking up solar energy - Superman Prime's abilities have all been enhanced & "super-charged" to the point that he is basically a god. He has absorbed so much solar energy that he glows yellow as a result, literally containing the power of a sun within his own body.
Although his appearances have been limited, it's quite possible that he is the most powerful living being in the DC One Million continuity.