and do I need a birth certificate?
If you have or can get a U.S .- State - Issued birth certificate that recorded his or her birth before age 5 then you must submit it
and will all this help with being able to claim an adopted kid for tax reasons?
If you want to claim your child for tax purposes while the adoption is still pending , contact the Internal Revenue Service for Form W-7A , Application for Taxpayer Identification Number for Pending U.S. Adoptions .