1. Absolutely yes. They not only develop sciences, but also meditate and evolve their souls, becoming stronger and more powerful in all the ways all the time.
2.If we are talking about our Gods, they are too advanced to allow killing each other for one reason or another.
Our enemies, who can be called "gods" only because of their greater development towards people and posing as the "one true god", dream of killing everyone who is not in their slavery, including the Gods. Based on their nature, their principles of interpersonal relationships must be pretty perverted.
3. Some things in ancient Indian books may be allegories. Here I can only say that as we develop and evolve, physical weapons begin to give way to spiritual ones.
In the sermons, you can find more accurate answers to these questions.