

I don’t recommend spray foam for a number of reasons, a few being that it offgasses VOCs after installation and can obscure or make future access to repairing surfaces impossible. If, for instance, water in your bathroom seeps into your subfloor, that repair becomes suddenly infinitely more complex if you have to fight through spray foam.
I highly recommend mineral wool batts, even if you do thin ones. They can be cut with a thrift store bread knife/any serrated knife and friction fit between the joists. Very easy install for an amateur, very forgiving. Save the spray foam for those tricky gaps next to doors and windows.
We bought ours from a local contractor supply store, and it was cheaper than Orange or Blue store and they delivered for free. Not sure where you’re at but search around.
Assuming you’re talking about leggings in the form of stretchy, form fitting pants, I would recommend going to a second hand clothing store and just picking out a bunch. Pick different sizes, different brands, different colors, and then try them on at home. A lot of second hand stores allow returns for clothing within a certain time frame and you will pay much less than you would for new ones, plus have a greater variety of brands to try on. Most department stores might have 3-5 different brands if that, some second hand stores will have a dozen or more. See what is comfortable and what you feel good in.
If you’re thinking of tights or the sheer or semi-sheer layer you wear under a skirt you’ll need to buy them new, and just get a size up from whatever size you think you might be. They are always too small!