Effectively none, though Xtreme Speed requires careful attention during Ambition Mode campaigns.
Achieving the Platinum trophy for is widely considered an "easy" but "extremely long" endeavor. While the difficulty is generally rated around a 3/10 , expect a significant time investment of 120 to 200+ hours to complete everything. Roadmap Overview
Your first step: (Wei, Wu, Shu, plus Jin) on any difficulty. Do not aim for Hard or Chaos yet — this is reconnaissance.
Every character has a proficiency level (1-50). You gain proficiency by defeating enemies and officers. However, there is a mechanic called "Weapon Affinity." Characters have a preferred weapon type (indicated by a star). Using a weapon they are proficient with levels them up much faster.