The latest Famitsu has details on Katamari Damacy Novita's download content. According to the magazine, the Vita launch title will get missions and song packs as post release download content.
While the magazine does not list pricing, it looks like with a little bit of work you can get at least some of the content for free. As you roll your Katamari about in the stages of play, you'll find items known as "Fan Spirits." They look like little pink people with hearts for their head. You can exchange 10 of these for free download content.
The Fan Spirits appear to be a sort of currency for buying download content. You can actually purchase the Fan Spirits at a rate of 50 yen for one, 130 yen for 3 and 200 yen for 5.
If you want more portable Katamari Damacy, it's up to you to decide between working for it by collecting the Fan Spirits, or taking the rich man's way out by just buying the Fan Spirits.
Famitsu mentions two download missions. One, due for release simultaneous with the game on 12/17, is called Snowman. Your mission is to build a four meter snowball. The other is called "Shopping" and involves picking up the most expensive goods for your katamari in five minutes. This one's release is currently date TBA.
Outside of download content, the game uses Vita's Near functionality for data transfers with friends. Via Near, you'll get the mission records of friends. If you beat these records, you'll earn candies which can be traded in for costumes.