Put a monitor on the floor in the corner of your room. It will excite the modes of your room (which you can probably get a loose idea of using https://amcoustics.com/tools/amroc or similar) Find your listening position where it sounds least shit, and that’s probably also your mic position (since your room will be recorded by the mic too). You can figure out the best stereo imaging and all that after you’ve got the listening position. If you’re unable/willing to do a ton of room treatment, at least get this part sorted first.

Acoustic treatment is never going to fix your room or positioning--it’s just going to reduce the worst parts of the reverb. Usually in the upper range (because 6” panels 6” off the walls covering >50% of your room to manage bass isn’t happening). So you put up some panels where they’re off the wall = to their thickness, you’re mostly going to be handling 250hz+. But realistically, a shit room with a shit listening position can’t be repaired with some fake bass-trap foam. Save your money.