how many folks know who Mitt Romney is?

Today on my plane trip I sat next to a young man from Layton, Utah. I started talking about Mitt Romney, and he wasn't familiar much at all with Mitt. That started me to thinking - What percentage of U.S. voters out there 1. have at least heard of Mitt Romney; 2. know some things about Mitt; 3. know he is looking at the 2008 Republican Presidential nomination; 4. (of those who know some things about Mitt) have a favorable impression of him?

At this stage in the game, what are the best and most efficient ways of increasing the number of folks in 4. above? Finally, what are the 3 most important messages grassroots folks can pass on about Mitt?