4.Is turning my set up 180 degree a must? or is there a way to do this right with this set up?
The issue is symmetry: If you can figure out another way to make that end of the room acoustically symmetrical, so that your right ear is the same distance from the right wall as your left ear is from the left wall, then that would work. You could maybe build some type of massive plug to cover that gap in front of the door.
3.If I turn my set up 180 degree, how can I treat the window?
You could have panels that you move into place in front of the windows when you need to do critical listening, and store some place else when you want natural light.
2.For bass trap, what can I do about that uneven space in the back (If I were to flip the arrangement)
Symmetry at the back of the room is not nearly so important as at the front. You don't need to worry about that. It won't have a big effect on how your ears perceive the direct sound from the speakers.
1.I can only afford 12 of 2"x2'x4' insulation, so I cant make 8ft long bass traps for all 4 corners, unless I make them 2" thick. What would be the best options (how many bass traps, how many panels) and placement with only 12 insulations?
I would use two of those panels at the first reflection points on the side walls and one as a "cloud", hanging above your desk on the first reflection point above you. That leaves 9. I would put one horizontally (instead of vertically) between the speakers and the front wall, to help with reflections and other artifacts from that wall. That leaves 8. I would use two in front of the window when needed for critical listening That leaves 6. I would use four of those for bass traps in the rear corners, arranged one above the other to cover the entire corner, floor to ceiling. The last two I would put as bass traps in the front corners of the room, at the top of the walls, where they meet the ceiling.
That should maximize the effectiveness of the panels.
Hope that helps!
- Stuart -