You can decide where photos take end up but tools like the Gallery tend to find any photos any where. This is a bit of aproblem if you have files that aren't photos and they all tend to show up as "albums"

Music depends a bit on which music application you use. Something like Poweramp lets you pick the specific location of files you want to use. Google Music lets you pick internal or external (i.e. plug in SD card) to store local copies of files.