Yes, faucet knobs turn.

you've probably already made your decision, but this would be appropriate for an average height four-year old, and is much more realistic than the molded plastic type.

In my opinion I think it would be alright for a 5 year old that height. The features on it like the sink and burners are big enough to be realistic. He would understand the "dishwasher better too".

No, although the buttons for the stove click when pressed / turned to sound authentic. There are no electronic / battery-powered noises, which is perfect if that's what you're looking for... quiet play time in the kitchen.

The company website says they are compliant with all regulations and do not use lead paint. So far the paint on mine has not chipped or even scratched. Unless your child somehow manages to peel off ALL the paint and eat it, there really shouldn't be any worry.