Speaker placement and Furniture -assitance needed

Hello all - I have a 13 x 16 room or a 15 x 15 room, i would like to setup my stereo in one of these room but i also want it to function as a sitting room for myself and when i have guest, the room has no tv or video considerations, although i ususally prefer the long wall for speakers i must use the short wall fi i use the 13x16 room, i have eliminated the possiblity of using the 15x15 room due to its square shape, i been told rooms with equal dimensions are not good for sound for some reason or another and my experience seems to confirm this, my main questions are-
1> is there a way to counteract the acoustic effects of the 15x15 room using only the foam acoustical panels, i would prefer not to have them but will bass traps help?
2> if i use the other room it is necessary that i place two chairs in the "sound field", they will be approx. 6 to 7 feet from the front baffles and will be close to the the same distance apart as the speakers, approx 7' all furniture will be leather (its a cat hair issue)
3> what are some possible effects of placing a sofa or chairs between the speakrers?

Also, the one of the long walls has a arch way that is approx 7'X 7' and is closer to the speakers and is probably where the speakers would first reflect, the other side has a glass door and windows, approx 8' in the middle, i have think curtains up now but i can get thicker ones if needed - SPeakers cannot be more than three feet from the wall to the front baffle, sofa and forementioned chairs will be on the other side
I will experiment a little this weeked but as i have not purchase the furniture yet it is somewhat difficult (i only have the sofa and some cloth chairs i can try it with
THANKS FOR ANY INPUT