Using in-house distribution for iOS testing / QA purpose

Question

I’m currently working in a large telecommunication holding. We are using multiple accounts with the Apple Developer Program for different companies in holding. This accounts have multiple applications.

We are facing now a challenge with our main IT provider, it’s has a huge testing team. In order to facilitate distribution of applications, we are thinking about enroll to Apple Enterprise Program. Using it for building “in-house distribution” for testing purpose, such as: develop, testing and QA environments. Also distributing this in-house builds over Firebase App Distribution improving the QA process. We hope that this configuration will help to avoid Device ID configuration and reconfiguration (when new testers join us or company workers that need test the apps), and facilitate provisioning profiles maintenance. For production, we need do as always, we use the classic distribution build for Testflight and App Store in all our currents apps.

This are my doubts about this approach:

• We can enroll in both Apple Enterprise Program and Apple Developer Program without problem? We will use same accounts?
• We should configure developers in both programs (developer certificates)? how about applications ids / bundles ids ?
• Distribution over Firebase App Distribution is secure enough to avoid undesirable installs? And it’s considered a valid distribution mechanism for Apple Enterprise Program enroll?

Thank you in advance!