If you truly don't know where he is or how to find him, you can file for divorce and serve him by publication. Assuming he doesn't respond, you can get a default judgment for dissolution of marriage. However, no financial issues will be addressed. Hire an experienced divorce attorney and he or she should be able to take care of this for you.
Officially, no. The attorney can represent one party and the other would be pro se (representing himself). Representing both parties in a divorce is basically a conflict of interest, even if there's complete agreement.
You should do separate wills and distribute your respective estates as you see fit. Keep in mind that jointly held assets will go to the survivor of you regardless of the will. You should consult an estate planning attorney to get more details and proper guidance.
Based on your question, I am guessing you do not have an attorney. Hire one now.
It is hard to say what their reasoning is behind the overtime issue, but an attorney will be able to sort it out for you.