Are leadership followers only NPC classes?

[Nail]

Exactly.

Moreover, I could see how a specific leader might attract specific kinds of followers. Considering how low-level these followers are, I doubt even a bunch of PC classed followers would make much of a difference.

I forget: are killed followers replaced? At what rate?

 

[Felix]

Considering how low-level these followers are, I doubt even a bunch of PC classed followers would make much of a difference.

I don't know why anyone would want a 1st level Rogue when you could have a 4th level expert with a skill list that's just as impressive. With more HP. And an extra feat.