I know you can get the alakamite there, any others?
Nope each vary on different things such as location, time, and if you completed the game or not.
Source: http://www.serebii.net/xy/megaevolutions.shtml
No. Only the Alakazite stone is there.
Here are the locations for all of the known Mega Stones: http://pokemondb.net/pokebase/163342/whats-the-location-of-all-mega-stones?show=163342#q163342
