Whenever you have bleeding edge hardware, you need the latest kernel for support. Mint is to my knowledge great for 1 year old hardware, but yeah it does take that 1 year. Might be good to try a rolling release or a more recent release such as Fedora. I use OpenSUSE personally and have never run into problems, albeit I currently do not have the amd chip.
Somewhere around 7-8 hours.
My use case is probably closest to a software engineer who doesn’t compile crazy stuff. A bunch of browser tabs, discord, zulip, and other chat services open, a terminal and VSC always open, with some quick compiling here and there.
I’m on OpenSUSE with GNOME and use TLP.
edit: I have the i5 1240p model