They do recommend washing anything that will come into contact with baby before use. So that's all clothes, sheets, towels, etc. New clothing etc can have chemicals left over from manufacture that can irritate baby's skin which is why they tell you to wash everything.

I didn't use a special powder, just my normal powder.

As for what to take to hosp, I have a combination of 4x0 and 3x0. My niece was 9lbs 6oz (2.45kg) at birth and fitted into both 4x0 and 3x0. She didn't last long in 4x0 but she did fit them for a few months after birth.

So I'd recommend taking both I guess! That's what I'm doing anyway.

Unless you have a premmie baby or a very small baby who might be too little for 4x0!