[MikeBmusic]

I would not change the flooring just for the sound but for aesthetics in which case go with solid wood if the usual basement moisture issue has been tamed .
Otherwise, just paint/stain the floor with a good concrete product, and use throw rugs for comfort and to dampen some reverberation.
Ceiling - rockwool in the cavities and then a double layer of sheetrock green-glued together. If you've got enough ceiling height, you can use rubber spacers, or even suspend a new ceiling not attached to the framing above.
Heating ductwork- you can wrap it in standard fiberglass, but if its noisy when running, the only real option is to turn it off when recording with mics.