They can't use their school ability in a duel, only skirmish or mass battle.

I blame the small font. I printed out a hard copy to read from and I've had a devil of the time.

Whups, sorry! I skimmed past your three questions. Let me try #2 and #3:
Several starting outfits don't match up properly with other parts of the School. (A couple come with bows but are missing arrows; others have no bows but come with arrows.) I think this is just a proof-reading error, and I'd let Hida Defenders start with appropriate armor.
Lots of Schools start their folks with Rank 2 Techniques. The book explicitly allows characters to use Techniques above their School Rank if those Techniques are granted as part of the School's starting Technique package. 

Crab Clan, Hida Family, and Hida Defender all come with +1 Earth. While this makes sense thematically it means anyone who wants to play a Hida who went to the Hida school is starting with less Ring ranks than others because you can't start with a 4. That's weird.
The Hida technique helps with Cumbersome armor...but the Hida don't get Cumbersome armor.  That's weird.
The Hida don't get a Shuji option to start with, which makes some sense, but they do start with a Kata they can't use til Rank 2 and that doesn't. That's weird.