-Yes. Because your H1 application is approved (you got the approval email), your kid's H4 extension application will base on your new H1 duration.Thus, you need to choose #2 "Yes" and #3, "No" in Part 3.
If my case is granted (I got e-mail from USCIS, but not in paper yet), I shoud check: yes and give the receipt number in question 2 of part 3, right?
-Correct.