NHS guidelines are to wash sheets, towels, underwear at 60. I normally use a scoop of vanish extra hygiene in there as well. I use persil non bio liquid, and I rub a bit of this onto stains before I wash them. Hot water sets stains so try and have a go at them in cold water first - and I keep a bottle of biological liquid on stand by for anything fairly badly stained (tomato sauce etc).
Forgot to say I only use 2 little scoops of powder (shot glass) as powder can clog up your machine and once a month I let it go on a 90c wash on its own with either a touch of bleach or white vinegar to wash the machine through
The way to check if your machine is full op is to load up and stick your hand in on top of the washing. You should be able to move tote hand up and down a good few inches. If you cannot do this, then it's over full!