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.

I'm afraid hardware upgrades for nearly all Apple iDevices are pretty much impossible... It's just the way Apple do things I'm afraid! There is the odd exception (e.g. new batteries for some devices) but there's nothing mainstream. I'm not aware of anyone offering a service to add 3G or up the memory on an iPad.
Sorry.

Sorry but there is no upgrading the hardware, what you got is what you got.

If you got the non-3G iPad but you want mobile internet access, either get an Android phone and data plan and use that as a data source for your iPad, or get a device such as the My-Wi 3G data access point.

As far as memory goes, no, if you genuinely need more storage on your iPad, you are going to have sell yours and buy a bigger one.