Any contractor or subcontractor who works on your house should be bonded, licensed, and insured properly according to state and local standards. Insurance can help protect you if your home gets damaged during construction or workers are hurt on site, while hiring a bonded contractor can help protect you if the contractor fails to pay workers, doesn't pay for permits, or doesn't finish the work. Here's more on how to do your research.
While it's easy to replace a light or faucet at a later date, you should have your contractor do the larger tasks at the same time. If you plan to replace the tub and install tile floor, it's best to do that all at once. You may save on labor charges if they can do a few tasks in one day instead of doing these tasks on separate days a few months apart.
There are so many beautiful things to notice about this bathroom that it's hard to know where to start. The concrete sink? The wallpaper? The sconce lighting? The tarnished mirror on the door, reflected in the main mirror? The barely-there ultra-modern faucets? Whatever you notice first, though, you can't but admit that this space is a masterpiece.