Oooh. Stylish. I'm not sure about Spell Resistance: No, as evocation spells usually permit it; I'd say yes to SR against the fire damage but not the suffocation.
Also, it's a Con check (not Fortitude) to keep holding your breath, and the phrasing of "suffocating those inside the next round who take a -2 penalty on their Fortitude checks" is a little unclear. (It seems to imply those who take a penalty will suffocate on the next round...) I'd suggest, "suffocating those inside, beginning in the next round [actually, I'm not sure what you mean by 'on the next round']. Constitution checks to continue holding one's breath are made at a -2 penalty."