I140 NEED TO TRANSFER OR NOT BEFORE GOING FOR STAMPING?

[abhimani]

Hi,
    I am in my seventh year.I am with company B that was a "successor in interest" for company A. So I became the employee of B in 2015. Since then my paystubs are from B and this year in April current H1B extension also approved from petitioner B until Dec 2019.
    With company A I have my I140 EB2 approved PD June 2013.    
    I am thinking of going to India for stamping this December (first visit since I came in 2011 with A's petition and valid stamping from XYZ) and have the following questions.
    1)I doubt that the VO might ask me to show proof of GC. If I show the previous I140 he might ask why B did not transfer to itself in last two years ?
    2) I have spoken to my attorney and B on issue 1) and they say VO should not ask as they just need approved petition for stamping.  Is this correct ? 
    3) Should I still ask them to file for I140 transfer to B because VO or POE might ask to show it ?
    4) Further the attorney says that "I140 once approved stays approved  and the only need to transfer to B would be when dates are about to become current but that has a long way to go. So do not worry as of now. Also because A company will never get closed its I140 will stay approved" . Is this correct ?

5) If I move to company D and because of some reason A closes its company then the only I-140 that I had is gone so that means PD lost forever ? 
    
Thanks