Q.498 If there were a multiclass Cleric8/Summoner2, could he take the Large evolution upon taking the 2nd level in summoner? The rules say,

"The summoner must be at least 8th level before selecting this evolution."
Does that mean he can take it since he is level 10 in total and also a summoner?

Q.499 How does a synthesist work when his Eidolon takes the mount evolution? Is it like the centaur in 3.5?