This is a brilliant question because the bag of sugar story is one of those forum legends that has a grain of truth wrapped in a lot of exaggeration, so let me pull the two apart as one patient to another.
Golf first, since it is what you actually care about. The honest range most people are quoted for returning to golf is roughly 4 to 6 months, and it comes back in stages: chipping and putting well before a full swing, because it is the big rotational load of the driver that the shoulder needs to be ready for. Swimming, especially anything overhead like front crawl, tends to come even later. Heavy or overhead work is generally held off for about 3 to 6 months while strength catches up with movement. So golf is not gone, it is a summer or so away, and your surgeon and physio set the actual date on your progress, not the calendar.
Now the weight thing, because this is where the myth needs gently correcting. For most anatomic totals there is not a single hard number you may never exceed for life. What there genuinely is, is a lasting bit of sense: avoid sudden heavy lifting, avoid repeated heavy overhead loading, and build up gradually rather than going from a sling to heaving a caravan hitch in one leap. The reason is wear and the socket component, not a tripwire at 1kg. Your club friend was almost certainly given a cautious early restriction that has been retold as a lifelong ban. Derek is right that a reverse gets firmer warnings about sudden and impact loads because of the dislocation risk, so the advice does differ by operation. Our page on going back to work after shoulder replacement goes through the lifting and overhead question properly, and what shoulder replacement will not fix is honest about the limits that do stay.
The one thing I will not do is put a kilo figure on your caravan hitch, because that is exactly the specific, examine-the-joint question only your surgeon can answer for your shoulder and your operation. Take the caravan and the golf clubs to your next review by name and ask them straight.