Solid Hardwood, Engineered and Laminate Flooring - Engineered, Glue or Float?

I've read tons of posts and have a question that has already been answered, but of course that just brings up more questions for me. :) I FINALLY decided on the wood which is over concrete slab in a one story house. I like Shaw's Artisan's Touch which is a 9/16th engineered with 9 plys. Anyone have any comments on this brands? We were going to do floating but since reading here I now have a few qualms about it like noise and having to use transitions because we will be doing nearly 1000 sq. ft. which is a family room, hallway, and 3 bedrooms. If we do glue down is it repairable if something happens to like the middle of the floor and if it is repairable, does it still look good or is floating a better option for that? Also, never thought much about the underlayment just knew we needed it so we want a moisture/sound one. A retail store showed me two and one was a piece of plastic with a bit of foam covering which was the cheaper option and the other one was a thin more foam-like cover which cost like .60/sq. ft. Is there a difference in the better of the two because with what we're doing and paying the $.35 difference doesn't really matter. Any hints, suggestions anyone could give would be greatly appreciated for this first time homebuyer. Thanks!