What's the best way to have a good hike on Mt. Huashan in a day time?

We will be in Xi'an from January 1st to 5th. 1) We're a little bit confused of which Peak to get to in order to best visit all the peaks. It seems the most doable option is to get the cable car to go up (either from the north peak or the west one) and then hike to the other ones.
2)Chosen the peak, how long would it take in total to hike all the peaks?4 hours?
3)If we get down without using the cable car which peak would you suggest to save time and get the bus/train back to Xi'an?

We're not afraid of difficulty, but just time constraints. Thank you in advance.