You've pretty much listed the categories of problems that occur.
1. Clothing. Every time I buy a pair of pants, I think, "does my dick look too prominent in this?" I don't mind showing a vague bulge, but thin pants, especially light-colored pants, create a problem. I've had some embarrassing comments from sales assistants over the years.
2. The physical discomfort. A large penis necessitates frequent discreet readjustments. Unless you get the right combination of underwear and pants, just walking around all day can become mountingly frustrating: too loose, and I flop around, getting frequent semi-erections, embarrassingly; too tight, and by the end of the day, my ball sack is aching and I just feel like stripping it all off and running screaming through the streets. Then there are certain exercises at the gym that I have had to cross off the list, because they involve me scrunching my junk up.
3. Reactions/Teasing. There must be thousands of posts about this topic, so I won't go into detail, but in summary: a small proportion of my friends, both male and female, seem to find a perverse delight in teasing me about it, and telling everyone they know about it, and they do this without any sense of it being inappropriate - because surely I'm secretly flattered, aren't I? Ok, it is sort of flattering, but it's still inappropriate. In addition to the reactions of other people, there's the internal sense of being a bit odd. Again, this is mostly an ego-boost ("Gee, I have to stand a lot further back from the urinal than everyone else. I rock.") but there are moments when you find yourself thinking that no-one else will understand certain things... hence this forum.
4. Time wasting. This has been mentioned above, and I have to agree: I don't know if it's size-related, but I've checked with a couple of my friends who are also well above average, and a few of my friends who are not, and those of us who are large tend to spend a lot more time playing with it. I wonder how much more I would have achieved by now if I had limited myself to masturbating once a day, for example.
S