It is up to you. They will not be out of status because timely filed request for an extension renders their stay authorized until the decision is issued.
Any request for an extension whether granted or not is always a consideration in future decisions to issue a nonimmigrant visa or grant admission.
Reasonable time. A week is probably reasonable. A month is probably not.
No. See my answer above.
NYC EXPERIENCED IMMIGRATION ATTORNEYS www.myattorneyusa.com; email: firstname.lastname@example.org; Phone: (866) 456-8654; Fax: 212-964-0440; Cell: 212-202-0325. The information contained in this answer is provided for informational purposes only, and should not be construed as legal advice on any subject matter.
Only you can decide whether to wait or not.
1. Status is governed by the I-94.
2. Depends on USCIS' decision and if a denial, how soon after it they leave the US.
You should retain an experienced immigration lawyer to review all the facts, advise you, and handle the case. You can find one through http://www.ailalawyer.com.
J Charles Ferrari Eng & Nishimura 213.622.2255 The statement above is general in nature and does not constitute legal advice, as not all the facts are known. You should retain an attorney to review all the facts specific to your case in order to receive advise specific to your case. The statement above does not create an attorney/client relationship. Answers on Avvo can only be general ones, as specific answers would require knowledge of all the facts. As such, they may or may not apply to the question.