From Chengdu to Leshan Giant Buddha, how to reach Leshan Giant Buddha fastest way ?

I'll be in CTU for 5 nights, planning to visit Leshan Giant Buddha. Which is the fastest transport to Leshan Giant Buddha from CD city - bus or train ? How long will it take if I take the bus & which station can i buy the tickets from?

Would it be possible to travel to Leshan Giant Buddha from CTU, visit the Giant Buddha & then travel back to CTU on the same day ? Thanks.