How will the immigrant visa case of my child be affected by my staying abroad for more than a year while waiting for a re-entry permit?

You have to prove that you have not abandoned and the law focuses on your intent at the time of departure. An absence of over one year is absolutely problematic but the fact you filed for a reentry permit is very helpful to show you had no intent to abandon. Try and get back as soon as possible because if your card is deemed abandoned, then the F2B petition must be denied.

Your green card should not be considered abandoned if you applied for the Reentry Permit. 15 months is a long time though, so you may want to call USCIS and check on the status.

If, by the time of her interview, you have abandoned your status in the U.S., she will not be issued a visa. If you resume your residence, she can get a visa. You should be admitted back into the U.S. with your green card, even now and even without a reentry permit, but you may be forced to show you did not abandon your status.