In this case, the L2 cache is part of the A7, so that would be fair. I would guess this means it's also only stored in NVRAM local to the SOC and not persisted to the general flash filesystem.
I would guess they just tacked a bog-standard TPM chip into their SoC design. Biometric (fingerprint) sensors and TPM chips go together; see any enterprise-targeted laptop from the last five years.
Quite. It'll be a little hardware black box that nobody can see into, one that just gives a 'yes' or 'no' answer.
Additionally -- if things are like they used to be when I was in the biometrics world in the mid-90s -- the fingerprint template will be small and work like a one way hash; if you have the template you cannot reconstruct the fingerprint from it. It wouldn't really be very useful to the NSA or anyone else.
