My plug is a pub bike so I generally don't need a bottle :) however I have used a seat post cage mount with out any problems (this kind of thing https://cyclinguphill.com/rear-mounted-bottle-cages/ ). For brake pads KoolStop salmon are always good. They do wear more than the black ones but braking is more even and they grip much better in the wet.
My plug is a pub bike so I generally don't need a bottle :) however I have used a seat post cage mount with out any problems (this kind of thing https://cyclinguphill.com/rear-mounted-bottle-cages/ ). For brake pads KoolStop salmon are always good. They do wear more than the black ones but braking is more even and they grip much better in the wet.