1) Yes, it is possible even through forbidden artifacts. Princess Aelina (or whatever her name is) also seems to belong to this category. It's approximately the same as creating a boss from a monster. Also, changing rare creatures.
2) The option of checking the artifact on the hero is good. But you will still have to change its description.
For example - Sword of Power = +2 to attack.
In this map: Armageddon's Blade = +10 to attack
If you add a difference of +8 to the hero's attack using a script, it will all work. But the description will still remain, and, if you put on Armageddon's Blade in another map, you will only get +2 to attack instead of the promised 10.
So, in my opinion, the first option is more convenient. We don't lose anything.