I have question about my private key and public key - where I can peep them in program (I can see them when I do paper backup - first 72 marks its my private key - root key, and second 72 marks is a public key - chain code, right ?)?
The root key and the chain code are
not the same thing. The root key together with the chain code allows Armory to generate an essentially infinite sequence of private and public keys (this is used in ordinary wallets). The first public key together with the chain code allows Armory to generate all the public keys, but not the private ones (this is used in watch-only wallets, they only contain the public keys, so you can see the BTC but not spend them)
Also when I do a digital backup my addresses are not backup? Cause why there is another options to backup my individual keys? Could you explain it to me? If I don't do a backup of my addresses I lose the money in them?
Both the digital and paper backups that Armory produces contain the root key and the chain code, so the backup protects all keys that Armory has generated in the wallet, and all keys Armory will generate in the future. The backup of "individual keys" is only for the very special case that you have manually imported keys into you wallet that are were not generated by Armory. That is a rare thing to do (and rarely a good idea).