@crypto_mentions, my answers to your questions below:
1. This encrypted on chain state storage is different from the off chain storage in the DHT mentioned in the white paper, correct?
2. Will secret contracts have encrypted state by default? In the Discovery release, will we be able to specify in a secret contract whether we want to store data on chain in the encrypted state or off chain in the DHT?
Yes, all secret contracts in Discovery will have encrypted state by default.
In the Discovery release, the off-chain storage will not be implemented yet, so you will only have the option to use the on-chain storage, if needed.
3. Will encrypted state apply to user defined structs as well (both on and off chain)? i.e. if I have an arbitrary custom struct, will I be able to store this in an encrypted format in either of these locations?
Tentatively yes, given the answer to #2 above.
4. Will we be able to access storage on and off chain from within Enigma callable functions?
Tentatively yes, same as above.