1) Having differences in the catalogues could be good, and might even add to the replay value of the game. Are you thinking of giving entries on different topics for the different factions, or giving entries with different viewpoints on the same topic (or a mix)?

One thing that I will caution you on, regardless of exactly how you implement the catalogue, is not to spend too long on it. The only game I play with a big system like this is Star Wars: The Old Republic, which has an in-game codex. You get new entries the first time you enter a new area, the first time you encounter a new species, and upon interacting with certain key individuals. And you know what? My first play session, when my Imperial Agent was making his way through Hutta, I stopped and read every single one. My second play session, and every session afterwards, I didn't read any of them - because they interrupted the gameplay.

If you want your players to get this information, the best way to do it would be to bring it up in game: through narration, dialogue, plot coupons, etc. Having some extra detail for the players that want it will certainly be a nice bonus for them, but you'll probably find that the people who read through every entry are a minority. Your time will almost certainly be better spent on core game aspects.

2) I agree with Des: show, don't tell. I'm assuming you've already heard the phrase 'one death is a tragedy, a million is a statistic'. You're asking which one has the most impact. Honestly, none of them have that much impact. You're asking me to imagine the deaths of tens of millions of people in one go - I can't even image ten million people all standing together in one space. It's just too big a number for me to get my head around. I'm not really going to care about them.

If you want impact, then your audience has to have an emotional investment - you need to make it personal.

Show us a soldier. Show him going through training, and how he spends longer being trained than he survives in his first fight. Then show us that his situation is hardly unique.

3) The answer to this question depends on exactly what you mean by 'prepare the students to defend the school against the enemy'. Are you meaning that they will be preparing (by learning to shoot) and that they will then defend the school (and everything else around) by fighting on far-flung battlefields so that the enemy never gets near the school? Or are you meaning that the school itself is in danger of being directly attacked?

In the first case, there is no reason to have live ammo lying around (and as Des has pointed out, some very compelling reasons not to have it).

In the second case, I can't see how they would be able to actually defend the place without live ammo. Training them up to do so, then withholding the actual weapons that they would need, would be a fairly pointless exercise.

- Irish

1) If you mean 'different factions see different things', well, on one hand, it makes the separate factions more interesting, but on the other hand it might make things annoying.
2) A million is a statistic. Show, don't tell.
3) None-training ammunition + children = dead people. It's stupid and not very safe, ICly. It says something about the people running the school, I reckon.