marbehsholom: I don’t know any smoker who doesn’t smoke during a “3 day yom tov”. They refrain on Shabbos only. Go to any yeshiva gedola and you will find the bochurim/yungerleit smoking. Is it right or correct? I personally think not. However, once someone is addicted, quitting “cold turkey” is difficult.
Eating ptcha, kishke, and other fatty maacholim are also problematic based on current medical knowledge and one might be oiver on “Venishmartem”. Does it fall under the aveirah category like “eating chazzer”? I am not so sure.