Try searching the forum with keywords for the information you want. There is a lot on microg, magisk etc.
It is possible to install magisk on /e/ and it involves extracting the boot image from the rom you used to install (search forum for how to do this, it’s all there somewhere, I may find a link to an old post for you ) e your current os.
Indeed /e/ comes with microg. It’s a system app. Quite often it helps for some bank apps to run without you having ever searched for it in the settings but it is worth looking at it and configure it how you want. Make sure all the tick boxes are checked in the self-check.
This post might help you: