How should I service a used 2015 Yamaha FZ-07: chain, fluids, brakes?

[SophiaSB]

I just bought a used 2015 Yamaha FZ-07 as my first motorcycle, and I want to learn how to do basic maintenance myself. The previous owner kept decent records, but I'm not entirely sure what's due. I'm comfortable with changing the oil and checking tire pressure, but I'm unsure about the chain. How often should I be cleaning and lubricating it, and what's the best product to use? Also, the brake fluid looks a bit dark in the reservoir window. Is that something a beginner can safely flush and replace, or should I leave that to a mechanic for now? I want to be safe and keep the bike in good shape.