The Peasants are revolting

[Warlord Adamus]

"Also I have been told to leave a fleet of 10 or more ships over the planet. Not sure if that works though."

Yes, it works. Here are the lines that make it work, located in the happiness.txt file.

Our Ship in Sector := -5
Our Ship in System := -3

Negative numbers are indicative of improving happiness.

[Tomgs]

Well for bloodthirsty races that takes a bit longer because you only get -2 and -1 for having ships in the sector and system. The quickest way to make the Bloodthirsty races happy is to declare war. -100 happiness for that.