where can i get a lid for the square cube tray? seems incomplete without a lid.

A lid on the square tray will serve no purpose. It works fine without a lid. The cubes are flat on the top anyway. As for clear ice, - NO, Lids do not create clear ice. To get clear ice you need to freeze from the top down so a lid would actually hinder the making of clear ice.

I’ve purchased two silicone molds. I'm getting the white ugly floaters from both, which rendered my drink completely undrinkable. Any residue left?

I have this problem too, but it's your water, not your molds. Easy fix, since the floaters are on the outside of the ice (at least they are for me). Give them a very quick rinse from the faucet and empty the glass. No more floaters.

Does these make the ice taste like plastic/silicone?

Not at all! It makes the perfect ice for cocktails.

If this product was bpa free, why wouldn’t you include that in product description??? seems odd

I don't think they are. It's not listed in the description anywhere so I wouldn't rely on them to be BPA-free. However, it's worth noting that "BPA-Free" products are not necessarily any safer, so I'd encourage you to do your own research.