you sure have a lot of Q´s... and I could give give yu answer to many of them... but being sooooo lenghty to post... I´ll check some links for you to read when you have time... or you can check tailfeathersnetwork dot com slash community... or talkcockatiels dot com... these two sites have LOTSA info about tiel care....

toxic paints, plants, fumes, food.... etc...

you can PM me anytime. I´ll be glad to help