To answer your question about system updates, it's almost always safe to update and there's no reason not to update as long as your CFW (Luma) is fully updated. System updates are only an issue on OFW, since the updates are basically just for patching the exploits used to get CFW in the first place.
As for the limitations of region changing, The Guide has that covered on their page for the process.
Another really important thing is that you should never follow any guide other than the one I previously linked. You especially should not follow a video guide because they get outdated very quickly and may promote old and/or unsafe methods of hacking the console.