Kingdom Cleansing (Matthew 21:18-22)

Christ is on his way back to Jerusalem on the dawn of a new day.  The previous day ended with Christ expressing an unfavorable opinion of the holy city, and so has a night of rest changed his perspective?  We notice that Christ curses a fig tree while returning to Jerusalem.  Why would Christ bother to curse a tree and then talk about faith?  What does faith have to do with the fig tree, and why is Christ cursing the fig tree?