It depends on what you're running in the background while the iPad is charging. The heavier the software/app you're running, the longer it takes to charge.
It also depends on how often you use the iPad. Over time, batteries tend to run down due to over-charging.
Charging; way too long! Discharging; way too SOON.
No you wouldn't have to unless your case interfered with the charging of your iPad.
Take your iPad the Apple Store, They may be a Problem with the 30pin Connecter on your iPad.
Your iPad will charge the fastest if connected to an power outlet. If you connect it to a computer for charging, depending on the computer, the iPad may not start charging until the computer is idle or "asleep." The charging time for any battery operated device always depends on how many times the battery has gone through the drain-charge cycle. For the relatively new iPad version 3, it may be as short as 30 minutes but again, depending on the condition of the battery, may take several hours to get a full charge. Also, keep in mind that the battery charge icon is not a direct measure of how much charge is left but a software interpretation of battery charge. In other words, it does take into account what you are doing so that the iPad can give you an appropriate warning of "5% charge" if you continue what you are doing.
4 years.
One weekend.
Depends on which iPad you have and how good your wi-fi is. I have iPad2 and it took me about 45 minutes.
3-5 days . maximum a week
find out yourself
30 to 40 min max
No, but on the iPad 2, 3, and iPad Mini there is.
24 hr.