That is a handy trick. In the original release a couple people had orcs kill Gareth in the barracks (for example), who is required for a minor quest. If his body is still around to resurrect, this would be easier than the alternative method (Reviving dead NPCs).
The latest game version added more NPCs to those protected from dying.

There were no official moding tools released for DD, and AFAIK nobody else has attempted to create any. The Larians used a mixture of tools to create the game, some of which were proprietary and couldn't be redistributed, with no unified interface and not a lot of user friendly features.

Some years ago they said it was possible moding tools might be released for DD2, but I don't know if developments since then have increased or decreased the chances of that.

Welcome to the forum.