ddd doesn't mount the disc and read files from it, it mounts the symbolic links which the consoles creates.
/vol/ contains the folder that the game needs to access, it's a mix of both disc and update. if you installed updates, ddd will dump them at the same time as it's part of /vol/.
I don't think there's access to the ticket, and it's not a restriction of ddd. it's more like a protection from nintendo to prevent access to more folders than needed at a given time.
Crediar said the "/system/0x/" folders are NOT part of the disc's folder architecture, he created their names to store the ticket info inside, but I don't know how to access that data from the console. it's not a folder or a file, it's maybe raw data extracted from the wud.