Perhaps current users of that system fare better than I did with mine years ago. It just seemed more like a barely functional system with issues, than a robust system you’d want to keep around for years of repeated use. The CO2 cartridges were vulnerable to leaking. Moreover it seemed to me that CO2 also escaped the keg through the friction seal between the tap stem and the bung.
To address your questions, I don’t know if there are actually two different versions, or just that the Deluxe package includes kegs, bungs, and CO2 cartridges.
I would be surprised if a CO2 cartridge lasted much more than one keg, but if it does you can turn the gas valve closed to move it to another keg.
Beer will stay fresh for weeks, if it holds CO2 pressure that long. My experience is that these things are better used, as the name implies, for parties where they will be emptied in a day or two, rather than as a full-time replacement for bottles or other keg solutions.
Oh and the last straw was the bulging kegs filled with primed beer that happened to sit in the cellar for a few months. Maybe I over-primed them (doubt it) or filled them before the beer was done fermenting (doubt it), but the kegs were ruint and the beer was essentially lost.
