I’m not a scientist, so I can only tell you my own experiences, and what I’ve read in householding tips, heard on the TV etc. Furthermore, YMMV, because I don’t know how different washing machines (and dry cleaning shops) are between your area and Germany.
But there’s a good site here Wet clean wool and silk (Also other tips about stain removal and cleaning).
Now, the different groups (I’ll list all, starting with the easiest: )
Cotton, polyester and mixtures: normal wash, 40 C (Our washing machines have temperatures in Celsius - how are your configured?)
Bed clothes, underwear, sweaty stuff: 60 C
90 C: not for normal usage, only for highly infectious diseases (scarlet fever, e.g.)
Saves money (Electricity and water) and washing powder.
Also, if you live in area with hard water, buy seperate de-calcifier to add, and use the washing powder dosage for soft water. Otherwise, you’re wasting washing powder to stop the calcite - bad for the enviroment, and your money.)
I also never use bleach, because I don’t need my white clothes to be sparkling white, natural white is fine enough for me. If you prefer whitey-white, only use bleaching powder once a while, though, only with these white things.
I also don’t use softener - cotton etc. is soft enough for me when I pull it on, and I don’t wear wool sweaters etc. directly on the skin, anyway.
Wool: depends on the type of wool. First, untreated wool (that smells “wool-like”, i.e. it has some lanolin=fat left in) doesn’t need to be washed every day like cotton (esp. as you won’t wear it directly on your body, because it scratches, so it won’t absorb as much sweat and body odour). Best treatment is to hang it outside in cool (night) air and let it regenerate itself. Every few months (if you wear it regularly) you can wash it, with a special wool washing soap (that will partly restore the lanolin) in the sink. Use** barely handwarm water**, and don’t rub or press - those two actions lead to felt.
If the label says the wool has been treated for machine-wash, go ahead.
This is where the age and sophistication of your washing machine plays also a great role - modern machines with sophisticated programs (at least here) can handle wool and other delicate wash much better than 10 year old models. (My friends mother has a new model, and washes all wool without any trouble).
Similar for silk and other delicate things: if you are unsure, get the special soap, lukewarm water in your sink, and be gentle. (Stain removal is an extra chapter).
One of the astonishing things I’ve read is that “dry-cleaning” shops not only use very dangerous chemicals (suspected carcinogens and similar), which may partly remain in the clothes (and then pass into your skin), but that they also use water! So you can go ahead in your sink without doing much worse.
Also, wash clothes seperately, as some clothes “bleed” their colours.
A little bit of vinegar (not the cooking kind, obviously) in the last rinse is generally a good replacement for softener, and is supposed to fix the colors a bit better (didn’t help me much, but then only a few of my clothes bleed.) BUT: don’t use vinegar for silk, I think that damages the proteins (more on the Care 2 site).
As for drying: a heavy wool sweater or similar shouldn’t be hung, but laid flat, on a dry towel (you can roll it in a towel to absorb the first excess water, that’s gentler than wringing it out.)
I never use a dryer, because for delicate clothes it’s too hot; it’s a waster of electric energy; and it costs money (I have to go to a self-service washing shop), while hanging the clothes in the air is for free. (Exception only if I need the dry clothes now.)
For nylons, things with paillettes and similar: the old trick is to use a pillow case (or an already ruined nylon pantyhose) and stuff the delicate things in there before putting them in the machine for the delicate things program. (Of course, you can buy special “nets”, if you want to spend the money.) This way, the little hooks in the machine, and the gremlins that eat the socks 
, can’t damage the paillettes etc.
Oh, about why the labels have changed over the last years: on a TV report (about the new “smart” poly-something sport clothes, which transport sweat faster away from the body, so you don’t feel wet and catch a cold), they mentioned that despite the label saying “30C, soft program”, 60 C was perfectly fine. They explained that the manufactureres are afraid of being sued (or getting complaints) if anything happens to their clothes during the wash, so they simply write impossible instructions, and now it’s the customers fault if he didn’t keep them. But they also know that realistically sport clothes are meant to be full of sweat, so 60 C will work.
If your clothes get little pills after washing, there are two possible reasons:
-cheap quality of the wool etc. Often, pilling starts after the third washing. Nothing much you can do about it, except razor them off.
-you used a too rough/hard program on your washing machine. Try either a softer program (30 C, for delicate things), or wash by hand. Or get a newer washing machine with better programs. (and one that saves electricity and water - it’s your money, isn’t it?)
Hope that helps.
