LOL - it sure sounds like you've got your hands full with all those birds. I love birdie laughs! My CAG, Jewel can sure get me laughing when she is laughing.
My B&G Macaw, Kia, will also screech whenever I'm on the phone. She hardly ever yells otherwise, but people always hear her when I'm trying to talk to them on the phone & they can't understand how I can put up with it. Since I don't talk on the phone that much, she really isn't hard to put up with <img src="/images/graemlins/smile.gif" alt="" />
As far as Ethel and the problems you are having when she is on your shoulder, you might have to make it a permanant ban and just not let her on at all. She will have a hard time understanding that you don't want her there sometimes, but other times its ok.
A couple of suggestions would be to simply remove her immediately every time she lands on your shoulder. I would be worried that if she bites your hand, she will also bite your face, so be careful removing her. The other option would be to make it uncomfortable on your shoulder so that she decides not to stay. A couple of suggestions would be to wear something that is very slippery (metal?) so that she has trouble perching or something sticky (like double sided tape) that she doesn't like the feel of.
Those are just quick suggestions off the top of my head, but maybe someone else here might have another suggestion.