Henning,
I can only say that all the directions above are quite correct. But we should not forget about the bichromate, that is more dangerous than the acid. Never touch its dry powder or a bleach bath with bare hands, especially if you have hangnails/scratches on skin. If it come in contact with your skin somehow, wash it of quick with plenty of water, and perhaps rub some baking soda over the spot. Keep it well locked, so no one could inadvertenly drink it (storing reagents in food containers, e. g. soda water - always bad idea). Yes, I also recommend bichromate bleach instead of permanganate - it works cleaner, on my opinion. I always mix 5l jug of the bleach, and take from it as much as I need for single development, then I pour the used bath away (we don't have here any service for proper disposal, alas).

Regards, Zhenya