1. It doesn't actually matter. Slayer is simplest.
2. It also doesn't matter. Weapon Focus, Piranha Strike, Assume most of the others are utility stuff (Skill Focus). Remember these people aren't just monsters, they're people with real stuff. If you don't assign a bunch of feats you can assume that they're used on their own personal things (Skill Focus: Craft (Sweet Rolls))
3. Ignore it. If the balance is a bit off the tables, don't worry about it - you'll notice if the monster has enough damage to just kill someone outright, otherwise they're just a strong threat. If they start doing vastl…