I know that the buying guides are updated occasionally. I think the last time was around the beginning of the year (Clint, don't hate me if I'm wrong). Though I think as new products are reviewed, they may be integrated into the recommendations.
As for your second question, at the two lower price points, I'm not sure you're going to see much difference in the receivers simply because the most sonic improvement will be in upgrading the speakers. The real difference between the 1k and 3k recommendations are the TV ($1500) and the speakers (+$500). Consider the other components interchangeable.