Personally, I can't stand wearing pantyhose. they don't keep my legs warm enough and they're so thin that things rub unpleasantly. I wear microfiber ballet tights from Bloch, Mikhail Baryishnakov, Capezio, and Danskin. I like either the Capezios or the Danskins the best, I can't ever remember unless I go look, but the tights are very soft and supple and have a matte finish.
For foundations it depends on the dress. But when I want to wear something I've been wearing an underwire shaper. It fits like a bodysuit built into an underwire bra. I can't recall the brand name and I bought it so long ago that I can't read the label, but I got it at Nordstrom. Other times I've worn a regular bra, and still other times I've worn a special bra that has all clear straps. At one point I wore a Merry Widow -- which is a long-line (extends over tops of hips) boned underwire bra. It was extremely comfortable and gave me a very smooth line.
Just make sure you don't get something so tight that you bulge out of it in funny places, that looks smooth under your dress and doesn't show any where, and most of all make sure you can move in it!!