Staying at the Ibis Xian Heping, 59 Heping Road Bei Lin, Beilin.

You can take a taxi , or take bus no. 30, 40, 14 or 25 (board at Huaxia Bank) to get to XA Railway Station. Walk to the east square of the railway station and take a tourist bus to the mountain. The buses have no fixed schedules and leave when all seats are taken. I remember you can buy round-trip ticket and it costs CNY70 or so.

How much would the taxi to XA Railway station cost and how long is the bus journey to the Mountain? Also how do I get back?

It costs you CNY9 to take a taxi from your hotel to XA Railway Station. If you buy the round-trip bus tickets, you can take the same bus back to XA in the afternoon. A one way trip to the mountain requires around 2h.