There should be plenty of internet stuff about the differences to watch out for when switching. As for migrating data, I found this topic here for a start … Migration of Backup of data from iOS or Android phone to /e/OS
https://www.androidcentral.com/antivirus-android-do-you-need-it
If you are missing an App, you can request it directly in the Apps installer, so that /e/ devs can have a look at adding it.
Be aware that since /e/ comes without the genuine Google services many Apps depend on, not every App out there will work reliably or at all. /e/ has an Open Source replacement in place which enables many Google-dependent Apps to run, but this has limits.
A popular App store combination apart from the built-in Apps installer are F-Droid, which only has Open Source Apps built from their sources, and Aurora Store, which is a Google Play Store client available via F-Droid, letting you install free of charge Play Store Apps anonymously (to access paid Apps you bought you need to login with a Google account).