As for the cats drinking out of the toilet, I don't let my cats do that if possible. It is not a good idea especially if you have some type of cleaning chemicals, etc., in your toilet bowl that could be hazardous to your cats health.
I've seen cats drink from water faucets, toilet bowls, etc., in various spots on tv and it is always funny to watch. I have even seen a few cats that knew how to use the bathroom on the toilet bowl and then flush the toilet. Wow, smart cat!

I would always be afraid they would fall in and then require a bath, though, myself.
It is necessary to have lots of clean, fresh water out and available to your cat at all times, though, as they need water. I think they like the sound of running water so that may be one reason why they drink from the faucet, etc. You can get water bowls that have the sound of running water now - a little expensive, but if they like it, then it is probably worth it.