How much does it cost to install a concrete floor such as this link:

http://www.lovejoyconstruction.com/conflrsealed.jpg

is it more or less than installing hard wood or ceramic tiles?

I wonder in this case if I already have a concrete slab, and have ceramic
tiles on, do I demolish the existing ceramic tiles and pour the concrete
flooring on top of the slab, or just polish and finish the existing slab?

I understand typically they will cut grooves, is this purely decorative or a
way to put in expansion joints?

Thanks,

MC