I have wooden stands for my monitors that sit on the desk. The stands are isolated by bubble-wrap, mouse pads and speakers sit on the pointy brass 'acorns' on the stand. Separate stands behind the desk would be better isolation, but in my case, would put them too far away.
Make sure your chair can adjust too. The perfect height for playing the keyboard may not be the perfect height for editing with a mouse.
I hang my headphones from above on a hook I made. This is hung from a swing-out lamp. The cable drops down from the hook, so it is never on the floor.
Find someone in your area that gives lessons in Alexander Technique. Have them give you your lesson in your studio at the mix position. They can sort you out for height and angles and so on. I know people who have had Alexander lessons for sitting on their horse, or getting in and out of cars.
I had a lesson to help me overcome some posture issues I was having at the drum set.
. “What you ask about is music. What you like is sound. Now music and sound are akin, but they are not the same.”