User blog comment:Jimeee/PS3 release dates for Dragonborn, Hearthfire and Dawnguard - Euro Update/@comment-166.137.156.18-20130207190351/@comment-3428817-20130209022924

Not sure about the PS3 versions, but here are the files sizes for the XB360 version. I'd assume they are the same, regardless of which console you have them on.

Dragonborn: 786.95MB

Hearthfire: 75.78MB

Dawnguard: 581.70MB

It's funny that Dawnguard is slightly larger, yet it's file size is smaller than Dragonborn.

@The Milkman: Hearthfire doesn't add any homes. With Hearthfire, you can buy land and design and build your own homestead.