labour certification & I140


I am an Indian citizen and have returned to India on October 28th 2015 after completing 5 years in USA on L1B with my family on L2.

Now my company is sending me on L1B again after I complete one year in India. They are also interested to file labour certification as I reach there.

I am looking forward to be in US in November-December 2016.

Here are my questions:

  1. Is there a minimum duration required to be present in US to apply for labour certification or I140 later?
  2. If my company applies for labour certification after I reach to US, will the same labour approval work if my company changes my status to H1B in future? If yes is this true for I-140 also?
  3. My understanding is that being from India (As the waiting time is more), I will need to change to H1B in order to stay in US continuously for more than 5 years. Is that true? 

Please suggest.