I never actually found cockatiels dusty enough to require airfilters, but then ofcourse that depends on the ventilation and size of the area you keep your birds. So I would say that it is okey to keep a cockatiel without an airfilter, and if you do find it too dusty i reccon a normal bathroom fan (that sucks out air) would be enough to place next to it dragging the air out of the house, that would require you to live in a hosue where you can drill a hole through the wall though. But I think regular vacuuming and sweeping around the cage area would be sufficient in basicly any home to keep the dustlevels under control with just one or two cockatiels.
I've found cockatiels extremely curious, if your drawing or whatever they just cant help themselves but they have to come to you and nibble that pencil... wich is a good way to get a bird to get close to you I think, by fiddling with something the bird becomes curiouse enough with to just have to check it out. And i would say cockatiels are quite easy to tame, atleast regarding to some other birds. but all birds can be tamed basicly. But every cockatiel I've met has been social (except those kept in aviarys as untamed birds). But I've seen em tamed by children and adults and everyone getting one to keep as a "pet" that i know has had a wellbehaved bird.
And i wouldnt consider buying a parent raised bird to be a problem, the only thing is that you got a little bit of extra work in thebeginning to get it to where a handraised baby would be, and that extra work doesnt meen more time spent than you would spend with the bird for the rest of its life, it just contains of different approaches and some "catching up". the time to get a bird to where a similar but handraised baby would be can be anything from two weeks and up to a couple of months, depending on the individual and how much time (correctly) spent with the bird.
this is gonna be a long post... anyways new topic
When you are at the breeder to choose a bird (if they got several) I would go for the bird that seems the most curiouse, for example if you stand outside the cage at some distance or outside the aviary or whatever and fiddle with your keys or something and you see one of the birds REALLY checking your keys out, almost looking as if he wanna come down and play with them but doesnt quite dare too, and there are 3 other birds turning the back and doesnt show any interest... I would go for the curiouse one...
Kind of the opposite when you choose a dog tho, where I would go for the one settling down and goes to sleep while your visiting.. saying that, if they all kinda freak out when you walk up to the cage to look at them and one of them settling down quicker than the rest that is also a good sign that he(or she) might be the one most comftible around you, which leads to you having an easier time to tame that bird, however sometimes color preference takes over, and even if it does, getting the bird that seems the most frighten does not by any means mean that that bird wont be tamed as well, just that you migth hve to be more gentle around him, and take it a little bit slower the first period of time the bird stays at you, but I do beleive the end result will be the same no matter what bird you choose. ofcorse with some deviation to the birds individual character..
