Well being as the colony ship just created a colony the previous turn, why did my approval drop completely from 100% to 56% after I 'magically built' all the improvements? 

In theory approval is tied to being able to make money. The turn I landed there were ZERO money making improvements, food improvements, or production ones. 

After we built all of them now everyone is unhappy. This makes no sense. 

And there is the ticket and winner. 

So the initial maintenance of all the buildings outweighs the $ I am making from them (at this point) until the population can catch up and make a larger tax base. 

I've been suspecting that maintenance has been a problem as well. Whenever I research a new generation of planet improvements (which have higher maintenance costs), my approval dropped.

I noticed the opposite happen when I upgraded farming improvements. My population gradually grew and started producing more money. Morale improved as well.

I now make a habit of adding money boosting modules to my starbases as a way to not only boost money, but approval as well. It seems to work well.