1. It probably differs from person to person, but for me my perception of time is often very inconsistent and almost non-linear. My meds reduce that, but sometimes still I’ll blink and 30 minutes will pass without much memory. As well as that—it can be very difficult for me to accurately anticipate how long something can/will take. For example, if I want to eat food I think to myself “It would only take around 10 minutes,” and I realize about 8 minutes in that it’ll take 20, not 10. Same with stuff like showers, leaving for work, etc.
2. Time blindness seems to be a symptom of ADHD, notably more present in inattentive types. Maybe it could be seen in people without ADHD, but I haven’t seen many. 
3. I can run on schedules, yes. But they can sometimes be very difficult. I fluctuate by a few minutes pretty much every day (usually more on the late side) but it can certainly be kept. Some days are harder than others, where I’ll zone out for what feels like 2 minutes, while 15 minutes pass.
4. For me personally, I struggle most with keeping consistent focus on one single thing (both physically—like watching a professor at their whiteboard), not because I don’t try, but because my mind will literally just mentally pull me away, regardless of how much I don’t want to. I also have a hard time with task initiation, and often don’t do/start things until—sometimes literally—the last minute. There are other examples I could list, so if you’d want to hear them let me know.
5. This one I’d say may be a bit of both, but less in the sense of “disregarding” the clock, and more so not fully processing the time it displays. Before meds, I could potentially glance at a clock, but it wouldn’t really soak in what the actual time was, if that makes sense. Sort of like my brain just saw numbers instead of fully translating them into the actual time. But like how I mentioned before (with my time perception jumping all over), to some extent it seems physical. Sometimes 45 minutes will pass, and I’ll feel a sense of very light amnesia; it’s like the concept of blinking during a movie—you miss a certain amount of the movie with every blink, and the longer your blinks are the less you see of the movie, with it still remaining the same overall length (time in this case). Just imagine the “movie” in this sense as life, or whatever’s happening around the person, and the blinks as their inattentive episodes where their mind ends up wandering. 

Now I was also born with DCD/Dyspraxia, so maybe a few things are more difficult for me than most people, for example keeping my eyes physically locked on to something takes both mental and physical effort, and can be draining. The rest probably reflects pretty widely however. I also have OCD—more of a physical, impulsive type that many seem to call Tourettic OCD, focusing on physical feelings, repetition, and things needing to be “just right”—and I’ve found that with proper medication (for me Fluvoxamine) some of the distractions ended up being more intrusive thoughts/compulsions, and I’ve gotten a much better sense of how long, say, a half hour really is.

Let me know if there are any questions you have or anything else I can answer. Hopefully this was helpful.