Answers (in short):
Regardless of whether you charge the same for everyone, or a tiered structure for kids/adults/long term members it must be transparent. No matter who tells who what they pay, it must be fair and in line with your policy. (See below for more details)
Some people who experience hardship deserve a break. As a business owner, you have an opportunity to make a difference in someone's life. This comes in the form of a scholarship.
Who gets one depends on you. If, after an honest conversation between you and the applicant, you feel you would like to award a scholarship, do it. Usually one year or monthly UFN.
How many scholarships to have available? After much thought I settled on 5 (random number of free memberships I felt I could handle)
Oh, one more thing. Announce on your website that you have a formal scholarship program as a community service to disadvantaged families. Call schools, members of parliament, tell Facebook, erect a sign out the front ... tell everyone what you do.
Who gets the scholarship and what the conditions are is highly confidential.
In general, be upfront and honest in your business dealings and you will sleep at night.
Post Script - Email me on firstname.lastname@example.org and I will send you the pricing chapter from the book "The Martial arts Of Business".
Or, you can get it here - http://martialartsofbusiness.bravenuweb.com/buythebook/