[Microsoft Surface] GoodDayToDie:
The thing you're thinking of buying is the Type Cover (the second generation one has backlit keys and is a bit thinner, but the first-gen one is cheaper and works fine). It's a full-size keyboard (that is, the keys are full-sized and at the usual spacing; it obviously doesn't have room for the full 104-ish keys of a desktop keyboard) plus a trackpad. It is not a case in any traditional sense, although it does work as a screen protector when "closed". It connects magnetically; removing it and reconnecting it is literally a snap (or perhaps "clack!") The magnets are strong enough you can fold the cover behind the tablet (although with the type cover this feels weird because the keys can move beneath your fingers, but at least they turn off automatically) or even dangle the tablet from the cover (not recommended but a cool trick anyhow).

Installing software is done the same way you would on any recent PC; you download it. The tablet has WiFi built in. There's a built-in store that can install and update "modern" apps, but you can also just download programs off the web/FTP servers/whatever. If you need to install off of an actual optical disk (CD or DVD) rather than a disk image (which Win8 can mount as a virtual drive), you will need an external optical drive that connects to the tablet using USB (there's a full-size USB3 port on the side of the Surface Pro). If you really need a wired network connection for some reason, you can get a USB Ethernet adaptor (they're only a few dollars) but that will take up the tablet's USB port. You can also use (USB) external hard disks or flashdrives with the tablet, as a way to transfer files including installers. I recommend getting a USB hub (ideally, one that can handle USB3) if you're going to use a lot of USB devices.

As for drawbacks, the biggest one is arguably that it's small. It's thick for a (modern) tablet, but at only 10.8" (about 28cm) diagonally, the screen is on the small size for a laptop. The case also doesn't have room for a lot of ports. You've got the aforementioned USB3 port, a miniDisplayPort, a headset (headphones+mic, like for a smartphone) port, a microSD card slot, the magnetic power connector (which is also where the stylus rests), and the magnetic cover port (which is how the covers send keyboard and mouse input to the tablet). No VGA (you can get a converter for the miniDP port, though), no surround sound output (the built-in speakers are ok for a tablet but nothing special), no serial or parallel ports (you can use a USB adaptor), no PS/2 port (USB adaptor), no wired Ethernet ports (USB adaptor), no card-reader for anything bigger than microSD (USB adaptor), nowhere to install additional storage or an optical drive (USB...), and only one USB port (hence the recommended USB hub). The Type (or Touch) covers offer very usably-sized keyboards, but a lot of keys are missing or require you to hold the Fn key at the same time. The next-biggest drawback is probably the price-to-specs ratio; while very attractive compared to other "ultrabooks" and high-end x86_64 tablets, you can get a more powerful actual laptop for half the price. The first-gen Pro also has a pretty mediocre battery life (5-ish hours) and a kickstand which only opens to one angle (which some people find to be not the correct angle for them). None of the internal components (battery, CPU, RAM, Flash storage, etc.) are removable/replaceable/upgradable, and the max specs of the original Pro (5GB of RAM, 128GB of internal Flash storage) aren't very impressive. There's also no dedicated graphics processor; the integrated Intel graphics are OK for light-to-moderate gaming, but not for serious gamers or any task requiring much GPU acceleration.

With all that said, it's a very nice, compact, lightweight 64-bit Windows computer with an excellent display (for the size), excellent stylus and touchscreen, very durable body (even without cover, though you really should get one anyhow), and good manufacturer support. It's usable as either a tablet or a laptop, and while it can't be said to be ideal for either, it's pretty good.

To give you any more advice on whether it's suitable would require knowing a lot more about why you're thinking of buying one and what you'd be doing with it.