Yes, there the same size!
Most cases, except for the hard clamshell type snap-cases will fit both the 2 gen and 3 gen iPad.
No, because the new iPad has magnets and the older one doesn't.
Yes! The only difference beetween a Ipad and a Ipad 3g is the technology
Not likely. Hard shell cases will have to be modified to fit the slightly thicker 3rd generation new iPad.
Generally the iPad 1 can't share the same case with iPad 2 except some specific case design for both ipad, such as the leather Bluetooth keyboard for ipad 1 ipad 2. A slip-style case that is strechy or a generic notebook case will fit both models. Since the iPad 1 is thicker, cases that hold the tablet with leather, metal or other rigid forms will not work. The iPad 1 will not work with the smart cover, or other compatible cases either, as it lacks the magnetic switches and edges.
It Will Fit Perfectly! It Would Even Fit with Bigger Cases!
No, an iPad 2 case will not fit an HP TouchPad. The dimensions and design of the two devices are different, making them incompatible with each other. Each tablet has unique button placements, camera locations, and overall shapes that require specific cases tailored to them.
No you wouldn't have to unless your case interfered with the charging of your iPad.
Buy a new one
If you have the iPad 2 or the new iPad, you have to have iOS version 5 and above to bypass the connecting to a computer. If you have the original iPad, this is not the case as it doesn't support iOS 5 and above.
Yup
The original iPad is 13.4mm. The new iPad 2 is 8.8mm, so it is much thinner.