The difference between Traits and Talents in Anime Tactical Simulator is that Traits are permanent stat modifiers rerolled through the Trait Manager, while Talents are a separate stat system rolled using Dice and Medals earned from Raids and Challenges.

To evolve a unit, you need a duplicate of that same unit, Souls that match its rarity, and Evolution Stones, all three at once rather than just one material.

Souls vary by rarity, an Epic-rarity unit needs Epic Souls to evolve, while a Mythic-rarity unit needs Mythic Souls, so the material itself scales with what you're trying to evolve.

Yes, you keep the Units, Traits, and materials included with my purchase, exactly as shown in the listing.