Any animal that has a brain and likes food can be taught to come to you for food. Stand a few feet away, shake or display food, call them over, and let them eat. Gradually move further and further back, and eventually you should be able to call them from any distance and have them come running.
To get them more comfortable with handling, you basically just have to acclimate them to it. Give them food if they'll step on your hand, and start out slowly with petting them, stopping whenever they get stressed. Eventually they should get used to more and more handling, and then you can pick them up and such. Works on most animals.
As far as litter training, it's a lot harder for birds (which just poop wherever) than for predatory mammals that are aware of their scent footprint. Look up how it's done for chickens and go from there, or just get tiny bird diapers.
