L1A - Role Change before initiating GC process

[sba2016]

Here is my situation and I would appreciate any help from forum members:
1) I am currently on L1A as people manager
2) Want to move to product management with title of manager but no people reporting - same employer
3) Green Card process not initiated so far

Trying to understand process:
1) Do my employer need to inform USCIS? If yes how lengthy process would be?
2) Can I still qualify for EB1-C after role change? I dont want to screw my chances so answer to this question is very important.
3) AFAIK Product manager who moved on L1 are eligible but they were product managers before moving

Thanks