Nidaros said "Remember though, if you have several planets colonized in the same solar system, the population from the colony ship will be evenly divided among the planets."

This is true of transports, but not colony ships. Colony ships unload only to the planet you select, whether previously colonized or not. (I just wanted to make sure a missunderstanding didn't develop.)

Here is a brief summary of the morale model in Galciv (for more detail see the documents in the online Encyclopedia):
1) Base morale is determined by planet class and planet population.
2) Morale drops as population increases, or with increased taxation.
3) Morale increases when you build certain social projects, research certain techs, discover and mine one type of galactic resource (the one that looks like a yellow box), survey certain anomalies, and build or buy certain trade goods.
4) Planet growth slows down as a planet's morale drops from 100% to below 50%. A planet will loose population if morale is below 40%.
5) If your treasury drops below $0bc your morale will start to drop (bringing the treasury back above $0bc reverses this trend until morale returns to where it was).
6) If your treasury drops below -%500bc everyone goes on strike and quits paying taxes.
7) If you colonize a planet with too many people its morale will be horid, so don't load up more colonists into a colony ship than you think a new colony can initially support.
There are other factors and affects, but these should be enough to get you started.

~SDC~