Bus 120 Wangfujing Bus Stop

I would like to take Bus 120 from Wangfujing to the South Gate of the Temple of Heaven:

1. Where exactly is the bus stop at Wangfujing?
2. How long is the journey on a Sun morning?
3. How frequently does the bus run?
4. If I use a Yikatong, do I swap the card on entry or on exit?

Thank you