Board Thread:Question and Answer/@comment-79.134.58.18-20150310082205/@comment-25151790-20150310092942

Your Alliance Hall gives you a bonus to the amount of experience you receive from your kingdom. For example, a building that gives 100 exp would give 102 exp with your level 2 hall. Leveling your Alliance Hall increases this exp bonus, and will also increase the amount of resources you receive when your hall is level 5 or higher. While it may seem like a large price for a small bonus, it benefits everyone in your alliance and adds up in the long run.

For Goddess Worship, each member needs to unlock the card on their own to receive the card when the gauge fills up and the goddess descends.

You can find more information about alliances in the Alliance article.