My answers to your concerns as follows:
1)Their will be no impact. You can renew your passport from your Embassy in US.
2)If you come back to your country, you can renew your passport holding the old one for your entry agin.
3)It is better to get new passport for your new born.
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Fadel fawzi LL.B, M.C.L., LL.M, Ph.D
Intrenational Lawyer & Immigration solicitor
ICU Immigration service center
http://www.icuimmigration.com