Here you go.

1. Yes.  Its good to bring these 2 fields on form and ignore all

2. Yes.  You can allow as that is the correct way forward

3. Life cycle mapping will not do the bulk updates. Before configuring this, need to sit with the functional / product owners/stack holders and confirm with them to make sure you are configuring this in a correct way.  The bulk updates can be done at any point of time if the things goes wrong via Fix scripts.  If you want to update the legacy field when there is a change in life cycle & vice-versa, use "Reverse sync choice" to true.

I hope this helps

Thanks,

Narsing