I haven’t used a standard alarm clock in ages. Lately it’s either been an electric timer plugged into the wall and attached to a bedside lamp, or a scheduling program on my computer that plays music at the specified wakeup time. The former has an analog control mechanism so that the first question really doesn’t apply, while the latter is trivially easy to reset, just by editing the appropriate configuration file.
In any case, I’ve recently been waking up before the alarm, often at such a ridiculously early hour as 4:00, so any anal alarm clock habits would fall under a different category than those mentioned in the OP. For example, I refuse to own an alarm clock that gives preferential treatment to one half of the day, that is, by including an LED indicator for post meridian but not for ante meridian, or vice versa. And even when I had a digital alarm clock that treated both halves of the day equally, I always preferred to set the display to 24-hour time, if that option were available.