There's one thing which has always raised a doubt to me. Suppose I have an album of around 100mb and I copy it to my SkyDrive folder, will it use double space in my system or will the album in the SkyDrive folder be a shortcut?
It is like an additional folder on your system, so double the space. If you just want to be able to access it occasionally, assuming your machine is on and connected to the internet, you can use their feature which allows you to download files not explicitly in the Skydrive folder