RTF is a global modification that replaces all towns in the game.

I would use the head of an Arcomage dragon.

In principle, it's possible, but in the fifth part, it's just a large lava dragon.

Added after 23 minutes
In general, you could make it so that it doesn't breathe fire, but instead throws a fireball like the Dark Witch, and the fireball would fly similarly to an Elven Druid's shot, but with a bit more fire.

Added after 3 minutes
I wanted to clarify, will the Chimera's Domain be similar to the Lizardfolk, but more humanoid? I mean, with spellcasters, Chimera Guardians, and Minotaurs (half-human).