No, even if Ditto has it's Hidden Ability, the baby Fletchling will have no chance of having it's Hidden Ability, if the Male/Female Fletchling does not have it's Hidden Ability.
>In Generation VI, any Pokémon, including male and genderless Pokémon, can pass down their Hidden Ability when bred with Ditto. Ditto's Ability is irrelevant to inheritance. If the male is bred with another Pokémon from the same egg group, Hidden Abilities will not be passed down.
Yes, it would have a chance of having it's Hidden Ability.
No, if both parents have their Hidden Ability the chance the child will also have it's Hidden Ability when it hatches is the same, thus it is not increased. If Ditto is one of the parents remember "Ditto's Ability is irrelevant to the inheritance".
Source for quote.