I have worked with several quakers. In my honest opinion, I greatly dislike them because of their attitude. I haven't met a friendly quaker. We had two of them at a store I worked at a few years ago. I am great with birds as it is and could usually break a new bird in less than a week. These two refused to be handled or worked with. They would get out of their cages and run a muck around the bird room. I tried over and over to no avail. I came to the point where I gave up. I had better luck handling the white doves we had than those two SOBs. Its easier to sell a friendly bird than a mean one. I have heard good stories about them however. They do have an ability to talk. As far as IDNs go, I haven't worked with them at all, so I cant say I have any prior experience.
As far as cold tolerance goes, fully understand that these are tropical animals and don't live in that type of climate. You need to do your best to keep them warm during the winter months. I recently bought a small conure. Normally winters in central Florida are on the warmer side. This year its been cold. Well in order to keep my bird warm I have had to run the heat constantly. I just got my electric bill and its over $200 because I was running the heater so long. Maybe I should invest in one of those small room heaters. Non the less, keep them warm. As creativity said, these aren't cheap pets. If you have never owned a bird before I would personally recommend getting something smaller like a parakeet, instead of jumping into larger birds such as the two you stated, But thats just me.