Get an african grey, any variety of amazon...lot's of midsized options. The big ones are the Macaws and Hyacinths.
Parrots are extremely expensive. If you find one that isn't, it's stolen or sick. They poop on the floor, but, I'll finish the questions anyway.
My son'e friend trained his African gray to poop in a kleenex on command. But if nobody was there and he needed to poop, that's what he did. As far as I know you can't potty train them.
They are extremely intelligent. Look up Alex the parrot on you-tube.
They eat pretty much anything but mostly seeds and nuts and not too many.
A big parrot will pwn a cat. A medium sized one will be fine.
Look here, these are all Medium sized birds and it also tells you more about the bird. I think your best bet is a Cockatiel if you want medium sized they cost around $80. But if you are willing to look for a small bird get a parakeet. I have one and three cats ( they know he is off limits) and they are sweet and loving and arnt to loud. they cost around $16-20
http://birds.about.com/od/mediumbirds/tp...
Parrots are loud and wont shut up. So think about your peace and quiet first.
I love birds, they are beutiful animals. But before I commit on buying one. I have questions I hope some can answer =)
1. What breed should I purchase? (I don't want too small or too big, medium sized)
2. I heard they where expensive, is this true?
3. Where do they poop? Sounds weird but I don't want poop on my floor
4. Can they be trained to use the bathroom in there cage?
5. Are they intelligent ?
6. How much do they eat?
7. My sister owns a cat... is that a problem ?