Yes, an award chart exists. It can be found at Use Marriott Rewards Points. Notice the link right in the middle of this page titled "Hotel Rewards by Category". Just click on that and you will see their new chart. Also, on the pop-up window with the chart, there is a link titled "View details of Marriott Rewards program changes." You might want to read through that to get an understanding of what changed within the program earlier this year.

Unfortunately, the answer to your second question is that Marriott has changed their hotel redemption strategy to more closely match their competitors. That means we now have a set "per night" point cost for an award and that doesn't change with more nights. (Other than for the redeem 4 get 5th night free.)