I have a Dataverse table where the Id column is a text datatype and I need to update it to an Autonumber datatype.

Before I update that column to autonumber, I want to understand the ramifications. As shown below, I already have over 2000 records that I migrated from a SharePoint source and in my Flow I copied the SP Id into the DV Id column.

Here are the options and I just need an auto-incrementing Id that will increment even if when I use a Patch and don't provide a value for the Id column.

My Questions:
1. Which options should I select to ensure I have an auto-incrementing Id column?
2. Will the existing values in the Id column resulting from migrating SP data using a Flow, get overwritten and re-ordered per the creating date?
3. Are there any blind spots I have missed?