Yes.
The ex-husband would have to be notified of the proceedings.
No you do not.
Once the divorce is final you can't go back and now ask for spousal support. Part of a divorce severing of economic ties. If spousal support wasn't part of the final decree, you are out of luck.
He could very well be arrested as he has failed to pay the support money, he shold pay then have a wife and child.
Personal interest is not tax deductible
Although the correct answer to your question may vary depending upon the jurisdiction, in most cases a reservation of spousal support means that whichever spouse has the reservation can come back to court and ask for more spousal support at a future date. In other words, the door is still open to allow a spouse to come back to court and get more spousal support for a longer period of time. Often courts require a change of circumstances from that which existed at the time of the divorce, for a spouse to come back to court and ask for more, however this is not always the case.
You haul his person back into the courtroom and the judge most likely will order him to pay or be held in contempt of court.
In California: If are legally divorced, you don't have to let your ex-spouse know anything regarding your personal life. However, if you are collecting spousal support from the other party, beware, your spousal support will terminate. If you plan on not telling him/her and decide to keep receiving spousal support, beware, once he/she finds out, you will be responsible for paying back the money going all the way back to your date of marriage (with new spouse).
from child support enforcement
yes
It would be necessary for her to file a civil suit in the county court where the non compliant spouse resides. The existence of a divorce decree is proof that alimony is owed but it is not given the length of time that has expired, valid for enforcing the support that was ordered.
Before you add another complication to your life, sort out the past. You need to put your new fiance into your financial picture, because she could end up helping you pay back the money--which would probably not be her choice.