What is the difference between experience and happiness levels?
The experience level is common for all your islands and it’s constant, you can only increase it. It is the measure of your general game progress. You gain experience from absolutelly all game activities and new levels always give you new opportunities: new buildings, quests, etc.
The happiness level is different for all islands and it may vary. It can increase and decrease. To gain happiness points, you should always build new decorations, social and entertainment buildings for your villagers. New happiness levels allow you to construct residential buildings and increase your population. Note that the number of your workers cannot be higher than your happiness level.
Why do the requirements for happiness level always increase when I want to build a new house?
New buildings give birth to more settlers. Your happiness level corresponds to the number of inhabitants in your village and cannot be lower than it. So to build a construction, first you need to reach a certain happiness level fitting the amount of villagers this construction will provide your island with. For example, to build a new villa that will add 3 villagers, your happiness level must be at least 3 levels higher than the current number of your population.
Do I lose any happiness points when I move buildings to the Warehouse?
Yes, according to the game rules, if you move any building into the Warehouse, you lose the happiness points that it provided.