Withdrawing and submitting a new form may be an issue depending on when your current B2 status is set to expire. Remember that in order to file a timely I-539 this must be received by the USCIS prior to the date on expiration on your I-94, not to be confused with your visa expiration.
An RFE will delay the process as this requires you to prepare a response however depending on the severity of the mistake there may not be any RFE. If the mistake is a material misrepresentation however then you will definitely want to inform the USCIS of this issue so as to avoid any potential immigration fraud concerns that could arise.
Legal disclaimer: The above statement is only intended to be general in nature and in no is to be taken as specific advice. A complete consideration of all facts is not possible in this setting and is necessary in order to provide any legal advice. This communication does not create any attorney-client relationship.
Yes, as RFE results in a delay.
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.