You must connect the iPad to the projector in the room as you would connect a laptop, via the cable provided. If you have an iPad1, this requires the Apple VGA Adapter (purchased separately for about $29). However, the iPad1 has very limited capabilities and there are only a few apps that can be mirrored on the big screen.
The iPad2, however, is a completely different story. With its VGA Adapter (purchased separately $39), once the device is plugged in, everything displayed on your iPad will be mirrored on the big screen. It is that simple.
However, if you are using a Smartboard, you will not be able to connect the iPad to the Smartboard because there is no USB port on the iPad. So the iPad image will display perfectly well on the Smartboard but the board itself will not have the interactive touch screen features. You would use the touch screen of the iPad instead.
It is also possible to do this wirelessly, but that requires the purchase of an Apple TV device ($99). Connecting Apple TV to the cables in the smart room or lab makes the iPad a wireless device, and any other iPads in the room can also access the Apple TV to display their images as well.
There are two basic categories: Wi-Fi and WiFi+3G.
Wi-Fi alone enables all of the functionality of the iPad as long as it is used in a location where there is a Wi-Fi connection. Without a Wi-Fi connection the device cannot connect to the internet and it use will be limited to those things that can be done without being online.
Wi-Fi+3G means that if you pay AT&T or Verizon for a monthly data plan (separate from any you may already have for a cell phone), you will be able to access the internet anywhere you have cellular service. The device will still be able to use any available Wi-Fi connection, but when one is not available, such as when in your car, it will connect via your cellular service to the internet.
Obviously, the Wi-Fi alone will be the least expensive to purchase and operate, starting at under $500. The Wi-Fi+3G not only starts at about $150 more, but you need to purchase the monthly cellular plan to take advantage of the 3G service. Without the 3G service, your iPad still works perfectly well as a Wi-Fi device. If you may have an intermittent need to use your iPad where there will be no Wi-Fi available for extended periods, it might be worth the extra money to purchase the 3G version. Otherwise, if it is unlikely that this will be the case, the Wi-Fi alone is probably all that you will need.
The other options are 16, 32 or 64GB. The iPad in not like a laptop or desktop computer where you need a great deal of storage space for all of the applications and files that you accumulate. Most everything will be stored remotely and accessed via the web, so unless you intend to be a power user with a massive number of Apps or use it in a unique way that would require the need for a larger storage capability, the lower end would likely be sufficient, considering you are adding about $100 more for each upgrade.
iCloud is the new service available (free for the base level) from Apple that enables you to store and access your content on their servers-the iCloud. This replaces the need in many cases for directly connecting a mobile device to a computer to transfer and access files. With an iCloud account all of your Apple devices and Macs (running Lion) are accessing the same content, so there is no need to worry about synching devices or repeatedly uploading and downloading files. You can read more about iCloud and view a video the demonstrates how this works. More Info.
That depends on how you plan to use your iPad.