Do useful things, like cleaning or studying.
no , but in general time is very important so you must take care of every second pass you must do effective things because Allah will ask you about every second .
Anything that enters the human body while you are fasting breaks your fast.
Regular medications should be okay while fasting. Check with your doctor.
NO, You can't chew gum while fasting. As soon as you chew a gum while fasting your fast will break. But, if you're in fast for weight loss then if you think that gum helps you then you can go for it.
When you are fasting you can not eat anything or drink.
----
Yes, of course. urinating doesn't break fasting.
coffee
No
When fasting, you cannot eat any solid foods. Most people fasting only drink. Broth, tea and vitamin water are three things you should consume while fasting.
Pillars of Fasting? You mean Rules/Regulations? While fasting, one can not be sick/on travel/on period(for women) Profuse bleeding, or throwing up will break your fast. While fasting, it is recommended that you not speak in vain. For more information, visit web site, alislam
From sunrise to sunset