[A930Rocket]

I've not had problems with grout in the corners, but silicone in the corners isn't a bad idea, as long as it matches well.

We always left the gap between the pan and the walls open to allow any moisture to escape.

Silicone at the joint of the shower pan (if you have one) and the floor tiles prevents squeaks there.

A tile floor and walls looks the best IMHO.