I'm no expert on the species, but I do have two books on Australian birds and they have some information on the Princess Parakeet :3
They need a lot of space as they like to fly. They are usually most active in the mornings and evenings, and they forage on the ground in search of their food. For the rest of the day they can sit with their heads tucked under their wings. The male has brigther plummage while the females is duller, also the females tail is shorter and more slender than that of the male.
They make popular aviary birds because of their gentle and fearless natures. They are also agreeable and trusting, but can be quite loud.
I hope this has helped you a bit
