Did you buy the one that was on eBay, with a bad electric gearbox? If so, congratulations, a real bargain I would say.
The tailstock barrel lock is a form of collet closer, mine is not locking very well even after cleaning, but to take it apart just unthread the handle and spin the front cap of the tailstock of.
Yes the chuck should be attached with a large threaded ring that pushes brass inserts against the spindle, so that it will not unthread as easily, as the lathe has brakes (if you bought the one with broken electric gearbox you might have an electric break through the VFD), it is a bit unsafe with just the normal threaded spindlenose.