Adjust status I-485 and I-864 affidavit of Support questions

I entered US on an M-1 visa. My i-94 departure card expired on March 27, 2007. I got married to a US citizen before that. I am filing for adjusting status. I am having trouble filing the i-864 affidavit of support. My husband does not meet the income

requirements (He is still a student) and has not filed for recent tax year because his income was too low and he is currently unemployed. He wrote a letter stating the reason.
He asked a friend to be a joint sponsor. However, His friend(USC) is already a petitioning sponsor for his wife and

they are going through getting his wife permanent residency as well. His wife stayed on a US visa waiver program however her stay expired. I am

aware that she could be deported since you are not allowed to stay over passed 90 days. They are going to see a US immigration official for an interview in June.

My following questions are :

1. If my husband's friend joint sponsors for me would it affect my application in any way?
2. What income requirement does my husband's friend(joint sponsor) have to meet? ($21,462=poverty guidline of 3

household size?)
3. How does husband's friend(joint sponsor) file for taxes ?
4. Would husban'ds friend (joint sponsor) include me as a dependent in his tax forms?
5. What are my husband's friend's(joint sponsor) specific obligations and requirements?
5. If my husband meets the income requirements within the next year, can my joint sponsor relinquish his obligations from
sponsoring me?
6. Would I also need to file an I-485a supplemental form since my i-94 expired on March 27,2007?(I HOPE NOT PLEASE SAY NO)

On this forum few people have detailed knowledge of US immigration. However, I think you will probably get helpful answers if you post on the US Marriage Visa Forum.

A few quick notes:

- It's perfectly ok for another US citizen living in the US to sign the affidavit of support. People do it all the time.
- If that person is already sponsoring someone else, the income requirement will most likely increase.
- You don't become someone's dependent only because they sign the affidavit of support for you. The only consequence is that if one day you get some welfare benefit the government will probably ask your sponsor for a refund.