Synchronizing a Zone from Original Onboarding to Transitions - Questions about the Sync Tool

Summary

Looking for clarity related to some behaviors.

Content

I have some questions regarding the Synchronization Tool (Configuration > Onboarding (Transitions) Administration > Synchronization Tool) that is available to help move data from Legacy Onboarding to Transitions.  Wondering if someone can help clarify some questions for me.

--BACKGROUND--
We ran the Synchronization Tool in our STAGING environment.  The following was observed as part of running the tool:
-It created a bunch of Custom Fields (UDF) in Recruiting > Candidate Personal Information
-User Defined Selection
-Forms
-Documents
-Message Templates
-Task
-Process

Some of this stuff is not applicable or necessary going forward.  As an example, the custom fields (UDFs).  We can easily delete that stuff as part of a clean up effort.