Add spouse into GC application in latter step

I’m current single but I plan to get married in the next 1-2 year.
I’m considering apply for EB2-NIW which has 2 steps: I-140 and IVP. I have two questions:

  1. I wonder when is the latest time that I can add my future spouse into my application? (I read somewhere that it is just before the IVP interview but not very sure)

  2. After I-140 get approved, I have 1 about year time-frame to response to the IVP. If during the time I want to switch into I-485 to adjust immigration status (I may get into US earlier on L1 visa), is it still possible? and in that case, can I postpone the I-485 filling to a longer extend (say 2-3 years)?