16:1 water:coffee ratio is a pretty common starting point. Your brew is pretty intense!

I’ve found that darker roasts are much nicer around 195F, I mainly brew very light roast and almost all of them come out under extracted at temps below 200F

Obviously immersion brewing is different than percolation, but the 16g water : 1g coffee ratio is exactly what James Hoffman recommends in his "Ultimate French Press Technique": https://www.youtube.com/watch?v=st571DYYTR8

For OP's light medium roast (dark roast prefers cooler temps) Hoffman says high temps aren't a problem and shows hard boiling water lead to peak brewing temperatures of 90-93C: https://www.youtube.com/watch?v=K_r5kpXPRYo Other youtubers have done blind taste tests and found they liked boiling water brews best with light roast coffee.

Not saying your taste is wrong either, just that OP is doing things a way described as ideal by at least one coffee expert! Lots of ways to brew.

206F/95C is the recommended temperature, some brew fine at 100C.

Obligatory James Hoffman link: https://www.youtube.com/watch?v=K_r5kpXPRYo

For dark roast yes, but for lighter roasts they are usually more dense and you could get a sour bree

Hot water is fine.