BrianH,
They seem to eat almost everything that they can get to. Every water plant that I have put in has been eaten. We used plastic milk bottles for pylons for boat races and they ate through one of them, there were teeth marks on all 4. Mine have been in the pond with tilapia since the beginning and even when feeding there seems to be not conflict. Mine are at about 5 pounds and I have about 20 to 25 and still nothing grows in the pond. I have a weed that sends out runners at a rate of 6" a day and as soon as it hits the water it is eaten. If I throw the same weed in the pond it might take over night before they touch it? They are fun to catch and good to eat. Except during the middle of the day they can be seen rolling at the surface all over my pond. I don't have any water temp info, I think meadowlark said something near tilapia, they have not bred in my pond, the book says they are difficult to breed and that coupled with the cold weather make them a safe bet in the US. They are a schooling fish and may have a way of communication. Catch one and it is difficult to catch the next. Might be two days before you will see the at the feeder. As I said they seem to eat anything, I feed 25% pellets, I also feed them fruits and vegetables, those that float.
I started with 100 1 3/4" fish, a poacher took 10 to 20 and I have removed the 45 to 55. My goal is to have 3 or 4 very big pacu. I don't know much of the info you requested unfortunetly, only my own limited experience. Mine have grown pretty fast, I have had them for a year and 9 months and the largest I have caught is 5 lb 9 oz, about a month ago.
http://scholar.lib.vt.edu/theses/available/etd-315812142975720/unrestricted/etd.pdf Here is some rainy day reading that might help.
