The phase problems are much more noticeable at the low frequencies. Try open the two out of phase tracks, one 100% to left, and the other, 100% to the right, and keep them in phase. See what happens, try to analyze the pure sound and its behaviour.
The Room modes can create ressonances and standing waves. The way to minimize its effects is to change the room proportions, an expensive solution, or try the find the ressonance frequencies, place a bass trap equalized with that frequence and get a little better sound.
You dont speake english very weel? We both. Where are you from?
Im an architect and audio fanatic from Brasil. Check my recording company, ok?
::. Area 13 Studios .::