an underlayment isnt needed on a glue-down ... with a properly prepared substrate an isntalled hardwood will have a solid sound. have the isntaller perform moisture testing of the slab and the wood to ensure its wihin standards and equalized prior to installation. for floaters I always install a vapro barrier because concrete will always breath and release vapor, even on elevated spans, and even though it might be minimal, you want protection from that. For glued down, unless there is moisture penetration above allowed levels (manufacturer stated) or significant hydrostatic pressure out of the slab (which shouldnt be an issue in an elevated span), then adhesives themselves are enough of a moisure retarder/barrier.

I have had floating cork throughout our finished basement for a year now and am happy with it. We have an 80lb dog, boys, and an insane cat and they have not damaged the floor yet. I have the Wickanders original floating floor which has a top layer of solid cork in natural color (obviously) over the locking base. The variety that you are looking at is a thin veneer over a layer of cork then the locking base. The style that I chose is not my favorite look but I wanted the thickest available solid top layer to have a better ability to withstand damage. Also note that any color besides the natural has been found by many to show wear quicker due to damage to the finish as red lover's floor has. While I like my floor for a basement I would not want it throughout the upstairs, in part because it is obviously a floating floor.

Under the appliances I ran the plywood only to where the legs of the appliance are and put flooring up to there so that the legs rest on the plywood and the edge of the appliances overhung the flooring. You really do not want to put the flooring down now as it will take a beating when you install the cabinets and appliances. Putting the plywood also gives you the opportunity to level the floor which makes installing the cabinets so much easier. Instead of leveling each cabinet you can shim the plywood to level in 8 foot sections, much easier than doing the cabinets in 24"-36" sections. You can chalk your lines on the wall off from your level floor and install the wall cabinets first so that the base cabinets are not in your way.

Marti - we have floating engineered hardwood over slab. Can you get anyone to see of you have any old plumbing buried in the slab that is leaking? This is be of the things we did. We had floating engineer wood from Summitt Forest Products. It had a nice handscraped look and none believes me when I say they are engineered. They don't look site finished but do not look like Pergo either. We had it glued near transitions to tile etc. Looks like you are stuck in analysis paralysis. Consider delegating this decision to another person who will just research and get it done and then you can move on to other things. I found that in our remodel, DH and I needed to delegate to one another a few times to take a break and get some distance. Good luck!