I think doing marketing for bitcoin is largely a waste of resources. You can talk with people and explain bitcoin to them if they seem interested, but sponsoring a racecar is like throwing away funds that could better be donated to individual bitcoin developers.
Bitcoin is an incredibly useful invention. Therefore it does not need a marketing team. It will spread by word of mouth and by increasing business adoption, because people will realize that it improves their lives.
Not necessarily, there are still a lot of people out there with the skills to help the Bitcoin community but are still largely unaware of its full potential. The Winklevoss twins didn't find out about Bitcoin until July 2012, for example.
I do agree that Bitcoin will grow without the need for marketing though. The technology itself is the marketing.
The Winklevii didn't become aware of Bitcoin because of a marketing campaign. They've met someone (forgot whom) who introduced them, so it was word of mouth. Ultimately I don't think that the Winklevii are true innovators in the bitcoin space, they merely help connecting the old fiat world to bitcoin until their investment vehicle becomes obsolete, because Bitcoin will be widespread and easy to use for the masses.
That evokes another aspect which isn't in favor of doing general marketing for Bitcoin: Bitcoin is not ready for the average Joe yet. So marketing Bitcoin to the general population could actually have negative effects, if non tech-savvy persons experience the lack of usability or even loose funds because they don't know how to secure them properly.
