Migration Assistant: does it transfer System Preferences choices; Favorites & Top Sites; Reading List; Preferences in apps like Mail or Safari?

Others have already responded to some of your questions.

The fastest and most reliable method for migration from an old to a new computer is through either a direct connection between the two computers (e.g. ethernet), or via a backup external drive, which can be Time Machine, "clone," etc. Migration Assistant asks you which method you are choosing to use, and then provides step by step instructions depending on your answer.

Before you migrate, Migration Assistant provides you with a candidate list of what to migrate. You can check or uncheck boxes by each item to indicate what you wish to migrate it or not migrate it. The options include individual users' files and folders, applications, settings and misc items.

Review of individual files, preferences etc. is not an option -- you migrate either the entire user or not. However you can choose to not migrate applications; in that case you would reinstall clean new versions, which may be helpful for situations where the version you were using under Mojave is not compatible with the latest operating system.

When you open Migration Assistant it will ask you a few questions including whether you want to migrate system and network settings, apps etc etc, just go and have look for yourself.

All is transferred unless you exclude during setup.