Overall it sounds like you are a bit overly concerned. The specifics of what a tripod is designed to handle depend a lot on the particular tripod, but in general, they are designed to hold weights up vertically and stable for extended periods of time.
Your first case is exactly what a tripod is designed to do. As long as the weight of the item does not exceed the rated capacity of the tripod, you should be fine. If the weight is heavier than the tripod is designed for, the stress may cause damage to the tripod or result in a failure.
Your second case, with most tripod designs, you are arguably marginally better off to stand it vertically. (I in fact store my tripod standing upright.) The only real concern with being upright when collapsed is that it isn't particularly stable, so you want to make sure it doesn't fall over (which could cause damage to the tripod or it's surroundings) but otherwise shouldn't be a problem at all.
The third case depends greatly on the tripod, it might not be advisable on cheaper tripods for lighter weights where one leg's joint might not be designed for that kind of force, but such tripods also tend to be very light themselves, so it is unlikely to cause serious harm.
The forth is specifically because of the weight attached to the head. Tripods are designed to handle vertical weight, not horizontal. The head may be very strong for weights pushing down on it, but when turned horizontal, the head is no longer designed to deal with the strain and may fail, dropping your camera to the floor and possibly breaking the tripod. I routinely carry my tripod over my shoulder like you describe and it causes no issues.
For the fifth, it might depending on the design and the weight. On my professional tripod, the legs have rubber caps on the ends to absorb when they are collapsed, but these do sometimes get knocked off when collapsing it quickly. In general, less shock is better than more shock, but again, probably not a serious threat to the tripod.
Finally, your sixth point likely has caused damage (and thus why it doesn't do anything anymore.) Most likely, there was previously a little clip (probably plastic) that latched the legs in place. This has probably since been destroyed and that's why it doesn't do anything if you don't press it anymore. That said, it's not really particularly meaningful damage since the tripod should hold it's position well enough by itself.
Overall, tripods, particularly any one of decent build quality, is designed to be a solid piece of stable hardware. It shouldn't break easily and should be able to take a lot of abuse. Don't intentionally abuse it more than you have to, but if it is a decent tripod, it shouldn't break from even fairly aggressive use.