What counts as a serious delinquency on your credit report?

All the things you mention are cause for concern, "serious" could be 30 days or 90 days, I guess that is for them to determine. Bankruptcy is worse then delinquency, both are horrible for creditworthiness. All delinquencies stay on your Report for 7 years. Longer delinquencies will have a greater negative effect then short ones.