Hello @sam_lay, welcome to the forum! 
Here is how we can help with the current challenges:
1. It is possible to skip Retool's native authentication, but only on an Enterprise plan, by setting up a Single Sign-On (SSO). Feel free to book a demo if you would like to see Retool's full potential with our top tier plan! 
2. Granular user permissions are achievable with "Permission Groups" on Business plan and above. 
3. Once we have different permissions set up for different user groups, we can totally redirect each group to a different homepage. Here is a doc on how to do it. In addition, I invite you to check this topic, where I demonstrate how to set this up step by step.
Let us know if you have any questions or if you are facing other challenges. The Community is here to help! 
