Whether something is deniable is not a matter of software features, but your acting skill.

No such thing.

CBP aren't stupid. If they see you have something like Truecrypt installed, then they will assume you have "deniable" stuff stored and will demand to see it. And if you don't actually have it? Too bad for you.

Cryptography cannot help you defeat a government's rubber host cryptanalysis.

You haven’t used Truecrypt, have you?