Would I be out of place by asking what exactly the auxiliaries do? My the questions include:
Are they limited to legacies?
No.
If not, how are the members selected?
Contact a local chapter for info.
How do mentors facilitate growth and leadership?
This is a larger question about what mentors do--you can probably google search to find out this information.
Are archonettes and amicettes usually previous pearlettes?
Not necessarily--a girl can join at any point based on her current age group.
The ideals that each member must strive for refers to ideals stated in the constiution, but at what ever level they are limited (e.g. high school students may not be able to help promote scholarship amoung college students)?
I'm sorry, but I don't understand your question.
I would have to say, even the basic description of them make the programs unique. Honestly, I am not trying to push anyone to be a member. It's just that the website is vague and I feel this, amoung many other programs distinguish this organization from any other. I'm aware that it says to contact local chapter. I really don't want to be judged for wanting to learn.
As proud as I am of our auxiliary groups, we are not the only organization to have them. How would you be judged if we ask you to contact a local chapter for information and you do so? If you are interested in finding out more about auxiliaries, please feel free to contact your nearest graduate chapter--they won't bite! 
I apologize if this is information I should not be asking. It wasn't my intention to offend anyone.