I-140 Current: Filed by previous employer when I was in H1B - Currently employed through F1 - CPT

[Sakthiraj]

Dear Murthy Law Firm advisors,

I was in United States between 2008 - 2017.   I have my I-140 filed through my previous employer in 2011 and my priority date is November 2011.  It is current now.   I went back to India on January 2018.  I came to United States after 6 years as a Graduate student in F1.  My course allows a full time CPT and I have joined a new employer through F1-CPT.  What are my best options? 

1.  If my previous employer hires me now, can I file I-485 with F1 status?  Or should I move into H1B status and then file I-485?  

2.  If my previous employer hires me and if I am in H1B, am I eligible to file I-485 without additional processes? Since I-140 was initially filed by that employer?

Kindly help me as I am waiting to bring my family based on this decision.  Thank you for your advise.