1. Calms last 2 years

2. Temples were left as they were, they were not torn down. This is very clearly shown in FF X-2. The residents of Besaid, including Wakka, kept the temple in good condition. The temple in Kilika was used as the New Yevon base. The temple in Djose was used as the Machine Faction base. The temple in Macalania was destroyed and sunk to the bottom of the sea. The temple in Bevele was abandoned. The Zanarkand Ruins became a tourist attraction. Requiem Temple is not shown, presumed to be abandoned. The Cavern of the Fayth(Yojimbo's) was nearly turned into a tourist attraction, but the fiends in the cave detered efforts.

3. All aeons were not required to complete the journey. The game is not completely clear on this, but it is supposed to be that Aeons from other temples are only training for the Final Aeon, nothing more, but then the lift(where you fight the Spectral Keeper) implies that you need the aeons to operate it. Anima was not important to the story, Anima was only important to Seymour's Backstory, nothing more.