The lamp does need changing. But in the meantime, given that it's been running for 25,000 hours, it's been on for 6 hours a day for more than 11 years.

According to the manufacturer, the cable has a length of 200cm / Black fabric cable.

No, (almost) no ceiling light will be able to do this. It is very rare that there is a socket on the ceiling, which is why ceiling lights are connected via a fixed connection. However, it should be possible to retrofit a cable with a plug if you know your way around.

This lamp is not dimmable.