Will there be any issue with my I-485 approval? If it gets denied, will my unlawful presence/out of status be counted from the time my I-94 expired? What should be my next steps?

I wanted to understand how Child Status Protection Act (CSPA) works in the case of employment based green card (EB-2) of the parent. My priority date is of 2012 under EB2, I-140 approved. Can CSPA be used to calculate child age when my EB2 priority date becomes current? Wondering what options I have when priority date becomes current and child age is 21+

If I change my employer, given the recent changes to I-140 rules for revocation/withdrawal, can my H1-B be extended again for 3 years, with me providing only the LIN number (which can be verified for an approved I-140 on the USCIS website) towards H1-B transfer to my new employer? Do I strictly need to provide the I-140 approval notice to extend/transfer my H1-B to a new employer?

My Project with My Client will end soon and my employer doesn't have any further projects and asking me to go back to my home country (India) by end of this month. My Visa is valid till Aug 2017 with extension filed. So I am considering to resign on last day of the assignment. ( no new employer found yet).<br>
1) as per new Rule would I be getting the grace period till my I 94 expires i.e till Aug 2017? Is this correct? ( 60 days grace period rule) Also during this Grace period Can I apply for a Change of Status to another non immigrant Visa - F1? (change to a different nonimmigrant classification.) if yes and F1 filed after termination of employment, will this not be considered as timely filed which can result in problems in the future?<br>
2) if F1 is filed Should I start my classes before I94 expiry date or can I Start in September or should I wait till F1 is approved ( after 90 days from date of filing F1)?