No. Updating the iPad's firmware will remove any jailbreak that has been installed.
Yes it can.
You have to have a jailbroken ipad and the app installous
Only the cost of your 3G dataplan, including possible overages.
There are many. The iPad must be 'jailbroken'. Jailbroken iPads are vulnerable to exploits, viruses and poorly written apps that can affect the iPad's stability or performance. Doing this may also affect your Apple warranty.
When you update your Ipad through iTunes or the App Store, all your games are saved. You can even recall the way the iPad was before the update if things don't work out right. If you have a jailbroken iPad and have done some 3rd party update, it may have deleted all your games.
It is possible if you have jailbroken your iPad to install software that allows for external control, file deletion and general bad-things-might-happen. If you are using iTunes to sync your iPad, then no.
It depends which iPad you have. The First Generation iPad can be Jailbroken using redsn0w (search on google) and the 2nd/3rd Generation iPads can be Jailbroken using Absinthe 2.0 (also search on google for download links, you need a pc for both methods)
Yes, you can bring a jailbroken iPod, iPhone, iPad, etc. into the Apple store and get it checked out. They 99% will give you a new product.
if jailbroken you can make the ipad detect a blue-tooth mouse changing a few settings... jailbraking = void guarantee
You can; use the App Store. Alternatively if your iPad is jailbroken you can also use Cydia to download applications that Apple wouldn't ever approve for their own store.
You probably updated your iPod and therefore causing your jailbreak to go bye bye.
You trade in your iPad 1 or 2 to the new iPad (3rd gen). Only that model has Siri.