Software Engineer to Product Manager

[usatourist]

All,

I am in a fix, really need your help.

I am on H1B and I have applied for my Green card (yet to get the i140 approved). While my GC is in process, I was told by my friend in the other team (same company) that there is a requirement for product manager and the hiring manager is willing to hire me. I have the following question

1) If I take that role do I have to file my H1B amendment? (Not a concern though)
2) Do I have to re start my entire GC process? (since the job description is totally different. You can imagine, Software Developer to Product manager (not dev/project manager)

3) Is it better to do after i140 approval or it is the same process irrespective of timing because of JD change.?

Hypothetical question.

Let's assume my i140 gets approved and I then change the company (Lets say company B - h1 transfer) to become a product manager in the new company (from software developer from Company A), Can I still port my priority date? There is a complete job description change here again.

I thought aspiration / promotion is a good thing to happen, but looks like on H1 it is not so :-(

Thanks in advance and Happy new year!