Would you like help finding SuperSU or custom ROM options for your specific device model instead?
You will likely need a custom recovery like TWRP (Team Win Recovery Project) to flash root binaries.
A: No. Any update will crash. Disable auto-update in Google Play Store for Magisk Manager.
Android 4.4.2 uses an older kernel that does not support modern mounting namespaces perfectly. You will not be able to use the latest Magisk modules that require API 21+. However, modules designed for KitKat work flawlessly.
Disclaimer: This guide is for educational purposes. Rooting voids warranties and may brick your device if done incorrectly. The author assumes no liability for data loss or hardware damage.