Is it normal for periods to be irregular after a d&c? i'm still waiting for my second cycle to start. i've been spotting off and on for a few days.

Yes: Absolutely normal for irregularities after a d&c - the biggest concern would be anemia with large amounts of bleeding so look out for excess fatigue.

Yes: yes, but the spotting could also result from retained endometrium or products of conception that weren't removed, particularly if you have continued lower abdominal pain or have developed a temperature. Be sure to followup with your practitioner if yes, and if spotting continues in any case.