Q: If I encrypt a directory, will I be the only one who can read it ?
A: Yes, only you would be able to read by entering the password that you created.
Q: If I copy the encrpted directory to an SD card, will it be unencrypted ?
A: No it will encrypted like before and stays that way unless you unencrypt it.
Q: If not, how can I have the SD card version unencrypted.
A: open the encrypted file or folder, and extract the data to the SD card.