they eat just about anything. Try not to give them too much frozen bloodworms but stuff like prawn, fish, daphnia, etc is fine. Feed them a flake or pellet food first and then offer some frozen food. This stops them becoming addicted to the frozen stuff and means they won't go on hunger strikes if you run out of frozen food.
festivums, severums, angels, discus, apistogrammas, catfish of all sorts, some of the bigger more peaceful tetras will all get along fine with them. They aren't agressive and as long as the other fish can handle the temperature (if you keep them above 28C) they are normally fine with most peaceful fish.
do regular water changes and try to limit temperature fluctuations during the water change. Keep the gravel clean and the water well filtered. They can eat a lot and make a mess if there isn't enough filtration.