I've only recently acquired an ipad, so I'm a newbie. Therefore, this may seem a rather dumb quesiton to those more familiar with the device. However, is it possible to upgrade the hardware without having to buy a whole new unit? For example, if the ipad I have has wifi, but not 3G can I get 3G added? Or if I have 16GB can I upgrade to 64GB? And, if hardware upgrades are possible, where can I get it done (do I have to send it to Apple or what)? Thanks.