Gaynor Sweater Tights sizing

I’m looking to understand if I should pick the size based on the info about height or size up as I’m not a typical ballet frame? I’m 5”6” so would select a Large by their sizing. But I also want them to be super stretchy and not inhibit my movement at all and I’m a size 12/14 Australian / New Zealand sizing. Want to make sure I have enough room in the thighs in particular? Also I am buying online and the colour in photos of “Elderberry” ranges from a deep red to a brownish burgundy. Any idea what it’s like in real life? Anyone got any recommendations?