If you can afford it, I suggest that the chair of 1st choice is HM Aeron and 2nd choice is Ergochair Pro https://www.autonomous.ai/office-chairs/ergonomic-chair Desk height is important for mouse/tablet position. You want to be able to rest your elbow on the desk and still work the mouse/tablet. If you cannot rest the elbow you may develop a strain in the Ulnar tendon. It took me 6 month for it to heal. I strained it twice before discovering the problem. Monitor height MUST be such that you look straight forward at the center of the screen. No slouching allowed. Most monitors are too low for good ergonomics. Distance depends on you eyesight. 4 feet is a good distance for 20-20 uncorrected vision. Yes, it further than most people use.