TimeCapsule

It acts like a server sharing a drive on your network. You can use the storage for putting files on it and you can use it for backups assuming you have enough space.

Assuming the TC is acting as your home router then you can access the files remotely if you enable that feature. If there's another router before the TC then the configuration gets more complicated. It may or may not be possible to access your files remotely.

 

Can I connect both a Mac & a PC to it? If so how can this be done?

 

There's a four-port ethernet switch on the back of the time capsule, you just plug in your network cables there to your computers, or connect via wifi. To get automatic backups on a PC you'd need to install additional software (I assume Apple supplies a PC version of Time Machine), but depending on how much stuff you have on your computers, 2TB may or may not be enough to keep a sufficient back-record.

My TC is just 1TB, so I use it exclusively to back up my Mac. The PC will have to make do on its own.