Share my experience with you, need your INSIGHTS and opions

Peview of my situation:
My exwife and I divorced on Jan, 04.

After that We filed child support, visitation on Feb, 2005. The final decree on child support was filed on Oct 2005, which was titiled: FINDINGS AND ORDER AFTER HEARING (Family Law-Custody and Support-Uniform Parentage).

During this crisis, my I-485 (Section Derivative, based on my exwife's employment) was approved on March, 2005.

Doubt about my eligibility of this "green card", I consulted with an immigration lawyer.
He stated that: In term of IMMIGRATION VIEWS, our marriage status last util Oct, 2005 when the LAST DECREE was filed. In another word, I have little problem to claim the green card based on our marriage even though we divorced while I-485 was pending. Also, he said the my status is Permanent Resident even though I did not claim the green card. He recomand me to file I-90 to claim the green card.

Question 1: Can I go get the green card with I-797 approval notice?
Question 2: Why should I need to file I-90 instead of using InfoPass?
Question 3: If I use InfoPass to make an appointment, which choice I should pick in the following

two related choices:
[] You wish to speak to an immigration officer.
[] You have received an approval letter or Form I-797 from the Service Center or local office instructing you to come into the office for alien identification card processing / passport stamp.

In other words, do I need to talk with the INS local officer, and tell him/her that I divorced during I-485 pending?


PLEASE SHARE YOUR INSIGHTS! THANK YOU!!