What is the temperature in Beijing in the end of Apr and how much is the taxi fee to the Great wall?

I will be going to Beijing on 30/4/11. what will the temp.I want to visit the juyongguan Great wall .what will be the taxi fare from Wangfuijing . after the Great wall what will be the taxi fare to Ming Tomb.Also after the Ming Tomb what will be taxi fare back to WangFuijing.