train or bus to Huashan

You mean you want to catch a train for the mountain and then go back to XA on the same day?

If so, I think time is a little bit tight, but if you hurry up, you may still catch the train at 11:00.
Since your flight lands at the airport at around 9am, you may reach the taxi station in around 09:20 and then take a taxi to your hotel in at least around 40 to 50 minutes. Then you need to take the local subway line 2 to North Railway Station from the south gate and this journey takes around thirty mintues. (From the gate south to the north railway station, you need to consider the time you walk from your hotel to the south gate station and the south gate station is called Yongningmen Station officially.)

Upon reaching Huashan North Railway Station, you need to take a local taxi to reach the foot of the mountain in around 15 minutes.

In my opinion, you can visit and stay one day in XA city and then head for Huashan on the next morning. In this way, you do not need to be in a hurry and you can enjoy the mountain scenery leisurely.

Hope the information can help you during the traveling.