Yeah I know . Sorry about that . The others were better for what you were looking to do than the one that works . the home site for the calcs is Alpha Certification . If you are really interested try a search .

As for the ceiling it should act a lot like a diffuser for high freqs . not necessarily a bad thing .

It is really difficult to say for certain what effect the beams will have on the low end . It could be positive or negative . The beams could create nulls or peaks in the low end . It really would be determined by your listening position which effect they would have .