in my case 14.00Kg. + nett 10Kg gas inside the bottle. Obviously the tare weight doesn't include the regulator. Regards the regulator I can only say that without one you will end up in orbit alongside the space station. There is a hell of a lot of energy in a full gas bottle. Qantas engineers will testify to that.
PS: Had an after thought here, above post was CO2 sorry about that, we are talking about LPG. With customer bottles the TW (tare weight) is mostly stamped on the protective shroud around the tap add 9Kg's to that and that what your bottle should weigh. If not you are being ripped off. As for a pressure gauge it would only tell you when your bottle is just about to expire. I would be more inclined to put my money into a second bottle as the are now cheap enough and always there as a standby providing of course you remember to keep it always filled up.