Installing Flooring

[Jerry S.]

I have a ranch style house with a concrete slab foundation. I'm want to put in either hardwood or engineered floors in the living room, hallway and 3 bedrooms. I need to use concrete leveler . What mil thickness vapor barrier if any would I need. I'm wanting to install either hardwood  which i think is out of the question (nothing to nail it to) or engineered flooring.  Would I have to glue the flooring down?  Are engineered floors able to float after they are installed?