on general design and representation of nature

I couldn't help noticing the clever photography and design throughout the movie: nature is constantly represented behind a plane, glass surface.
Notice the constant paintings and photos representing nature scenes on walls behind the characters. Either that, or trees / plants / mountains / open vistas appear behind overtures such as doors or windows. The first part of the story abunds in potted plants, fake cascades, fruit salad and so on.
Even when our-fabulous-Julianne arrives at the commune, the sort of triptych behind the leader's lectern represents some sort of palm tree.
Once you spot this leitmotiv, you will hardly see anything else.

In other words, primordial nature (I know, this is redundant) has been relegated to a background to this (80s) modern, industrial society.

Of great interest is the remark by the protagonist near the end when she comments on the landscape ("this is so beautiful"); The camera pans to reveal... some sort of canyon, an arid desert devoid of green, luxurious vegetation. There ain't no waterfall here, no monkeys skipping from branch to branch, no multicoloured parrots and so on. Of course, the flowers that Our Julianne tended to at the start of the story have also faded away.
...Has the modern, rich world lost its connection to Mother Nature?

Visually, there is a lot of static, rectangular framing going on -for example, Our Julianne sat still in her brand new gigantic sofa.
The final scene has her staring into a slab of a mirror, her head neatly entombed into the rectangle -this could be the Kidman character of "Eyes Wide Shut"!
Haynes tends to go for the Ozu -or even Noe- approach at times: static, cold, training his camera on his characters left exposed with nowhere to go, no diversionary action to take.
Buildings are often modern, desensitizing, not comfortable to the characters -cf. Antonioni's "Red Desert".
You may also want to check Boris Vian's "l'Arrache-Coeur" novel.

etc.
In short, some great conceptual work here!