Leadership: Depending on the cohort, I don't yet have a problem. I'll let you know if there ever is an issue in terms of power level, and right away I don't want them to do more than support a need the party has (ie: a healbot would be fine but a do-everything wizard wouldn't be; though a sage who makes low-level scrolls or only knowledge checks isn't a bad idea; a monster is likely fine, depending on what it is).
Leveling: I don't know. If the group gels together and we have fun, I may do one of two things: 1) go E6 and have everyone add a feat every 5000xp. or 2) try out one of the lesser-known level up options from the FRCS, or something similar. or (three things) 3) try letting people just add levels and go ridiculous.
I'm leaning towards E20 (feats), but I don't know. 4) is quit the game and start again with lower level characters. The scenario might finish off the setting, I don't know.
Creating an army: I kind of like this idea. I also have the 3e Stronghold builder's guidebook, and I've always wanted to try that out. Maybe this will be a good time for that.
Let's start off slowly, though. We can do those things later.
Question: do you folks want to start off as a group? Do you have one headquarters you work from, or individual keeps, towers and fortresses?