I think #2 should be #1, it is insane on how many people can not articulate what their website is about in a sentence or two. It becomes so frustrating for a brand new user to visit a website and reads a bunch of marketing gibberish. Sometimes I think that a good test would be to have a 7 year old come to home page of the website. Let him look around and then report back to you what the website is about. :)
I spun out a quick rant on HN some time back which became among my most popular comments of all time. Eventually posted it as an article on its on, "Please Forward to Marketing":
http://www.reddit.com/r/dredmorbius/comments/27d5xr/please_f...
Tell me what the fuck it is EVERY GODDAMNED TIME YOU COMMUNICATE ABOUT THE PRODUCT. It doesn't have to be long or detailed, you can link to your detailed description in the communication. But your press releases, emails, Tweets, blog posts, marketing collateral, etc., are going to get passed around, word-of-mouthed, and/or pulled out of drawers (or browser history / searches) for weeks, months, and years to come. Make them work for you. A link back to your primary site should be present where at all possible -- in your Twitter profile if not the Tweet itself. Absolutely include links to your primary site from blog posts.
.... and more.