1. I kind of doubt that the beastmaster is a vegetarian. Herbivores are bottom of the food chain, and the beastmaster's playstyle is rather aggressive.
2. What do you mean,
most clerical women? I doubt all religions condemn their priestesses for wearing clothing more fit to be worn in a desert. She probably is able to dress that way for a reason:
Priestesses are healers, and so is Asyra, their goddess. I can imagine that they place a lot of value on the body, and that they don't try to "hide" their bodies. They probably only use clothing for the purposes of ceremony, weather, and expression. The reason that the male priest doesn't wear clothing like the priestess does is probably because he's a priest of Malakai, rather than directly serving Asyra. While Asyra is a deity of healing, Malakai is a deity oriented more towards attacking. The clothing of a Malakai priest would be less revealing and less form-fitting, and therefore having less emphasis on the body.
Or that's what I'm guessing, anyway.
3. It's not that they don't use magic in wars at all, it's that magic use in conflict is restricted. I'm assuming that the members of the Dawnlight Compact have enough military power and magical might to threaten other nations into conforming to the Mage Wars institution. If anyone were to go against it and use too much magic in a battle, I can imagine it would be like if a country in the real world threw a nuclear bomb. Suddenly everyone would be using the bombs, and it would be a nuclear war.
4. They're not. But if they decided to ignore the Mage Wars institution, they'd be facing the combined magical might of Sortilege, Westlocke and Straywood. The Mage Wars are useful to warlocks for scouting their enemies, so that they can better prepare for if and when they break away from the Mage Wars institution and wage war on the world. At least, that's what it sounded like to me.
http://magewars.com/jsite/detailed-overview/world-of-etheria