I recommend starting at a 15:1 water to coffee ratio and adjusting over time as you see fit. This means for 55g of coffee, you'll use 825g of water. A standard cup of coffee is around 355ml and we all remember from chemistry that 1ml of water weighs 1g so you can do the math based on the size of your french press and how much coffee you need.
If this is too complicated for you, then just experiment and adjust for taste but make sure you remember what you did last time so you can tweak it!
This brings the water down to an ideal 200 degrees. If you pour the water right off the burner, you risk scorching some of the coffee.
I highly recommend decanting all of the coffee immediately instead of leaving it in the press and coming back later. The coffee in the press is still extracting so you want to remove it from the grounds as soon as possible.