Transferring H1B to client in 7th year H1B

[swagath_22]

I have completed Six years of H-1B and recently my H1B got renewed based on I140 (EB2 category) and got extension until 2017. The situation here is, I have got a full time offer at my client location because i am working from last 6 years for them and they are ready sponsor H1B.  But the only problem is they will file my GC in EB3 category. I have checked with my employer and he is not going revoke approved I140 and he is ok to continue GC process if I take full time also. The only option my client gave me is I can port the dates.
Questions:

1) Can I take full time in the above situation? 

2) Lets say if the dates get current can I file I485 with my previous employer?

3) Lets say if I485 or GC gets approved how can transfer to EAD status if I am in FT with Client?

Can you please help me with these questions?

 

[swagath_22]

Need help with above situation.