H1B Extension 6th Year RFE - I 140 approved

[Mummidi]

Hi,

My max out date happens to be June 6th 2018 and I 94 expired on Aug 28th 2017 and H1B extension till the max out date was applied by my current employer before I 94 expired.   When extension was filed my GC PERM was in process and when RFE received in Dec'2017 at same time my I-140 is approved.   Now I heard that I-140 approval document is not being attached in RFE response going to be filed by my employer in a week or 2.  

I have below assumptions on my current situation on extension, Kindly clarify.

1) Applying 240 day rule on my I-94 expiry, incase if the USCIS decision still pending by 04/25/2018 then I believe I need to leave US by that time. Is this correct. 

2) My understanding is if the I-140 is not going to be attached in extension RFE response to be filed, then I might get extension approved till max out date which is June 6th 2018. Please correct me if I'm wrong.    If this is the case, I need to be prepare to file for 7th year extension with I-140 attached.  Is this correct.  

If above my understanding is correct, I have very tight dates along with high chances of leaving US.