International divorce / custody issue

I'm not going to bore you with all of the details in my case but suffice it to say:

1) I married an Italian citizen in November of 1996 while stationed overseas in the military.
2) We have since had 2 children, 1 born in 2000 in California, 1 born in 2003 in Italy.
3) In 2004 my wife took the kids and went back home to Italy.
4) I have been working off an on trying to get her to bring the kids back but she refuses.
5) During this time, my wife has been able to go online and file for child support via the electronic child support filing system in California. I did not contest being the father of my children and have subsequently been paying child support for them at a 100% rate as the child support system decided that since I don't have physical custody of the children, I should pay the maximum.
6) Since, I have been unable to serve my wife with divorce papers and pursue child custody through the court system because I can't even show proof of delivery, I have no physical address for her.

So here are my questions:

1) What options do I have in order to get child visitation / custody established AND enforced so that I can force her to let me see my kids and know where they are and how they are doing? If I can't serve her divorce paperwork, how can I get this done?

2) How can I work on my child support payments so that I can actually afford to cross the pond to see them given that they live in Italy, somewhere, with their mother?

[Gbyte]

Do you have an attorney? These sound like questions for an attorney skilled in international custody issues. You can post to the ask an attorney section for $10.00. They may be able to provide much needed guidance.