Filing I-485 after PD being current for almost 14 months (delayed filing)

[priya12345]

Hello There -
The PD of Sept 2010 has been current in visa bulletin since June 2021. Its been 14 months already with PD being current.    My I-140 is in revoked status and I'm thinking to talk to my past employer to get GC process started again.             
Do we apply I-140 and I-485 concurrently or file it separately ?                
If we apply I-140 first and get it approved and If we apply for I-485 now after more than a year of PD being current with new approved I-140 then how do we justify delayed filing ?                
Note : I was outside the country prior to Jan 2022 and I am pursuing new masters program from Jan 2022.                
What are the chances of getting I-485 approval?                
If I-485 gets denied for any reason what is the next steps ? Can we refile it with same I-140& employer letter or move to new employer and then file it again with same PD ?                
Also to do this above can we get H1 B extension even after I-485 gets denied ?        

 

Please help/advise.