ranges from 40(legendary dogs) to 70(ho-oh for you, mewtwo, ect.)
Dialga does not evolve. All legendary Pokemon don't.
Latios
Well, I guess you mean "Soul Silver", and the main legendary Pokemon is Lugia, Water/Flying-Type.
the only legendary that you can breed is manaphy. and that will result in a phione.
In Pokemon Soul Silver, Suicune is at level 40! ^_^
Moltas: the fire legendary bird Pokemon the second strongest bird Pokemon
You can't breed legendary Pokemon eggs on Pokemon SoulSilver or on any Pokemon game.
over 9000
They will simply gain Exp. You can't breed legendary pokemon.
no
It might depend on the Pokemon, though usually you can face legendary Pokemon again if you beat the Champion.
Probably either Mewtwo or Rayquaza.