Ok, so I will obviously need those affidavits.
Here are a few questions:
1. do they have to be handwritten?
2. do they have to be notarized?
3. do they have to be from people that are not related to you (no family)?
4. what kind of evidence do they want in support of the affidavits? (I really don't understand that one...)

http://www.visajourney.com/forums/index.ph...p;page=751guide
You do not have to have all of the types listed below as proof of the relationship, just supply as many as you can. If you are short on the documents that have both of your names listed on them you MAY include affidavits from people who know you as a couple (see examples), confirming your marital relationship -- note that they are not required. If you have very little documentary evidence, you may find affidavits helpful.

I personally do not think affidavits are always appropriate. I didn't want to ask people to do it either, and I researched several opinions including 2 immigration lawyers' before I came to my conclusion. Our I-751 was approved without interview.

Other people have had plenty of documentary evidence and included affidavits and been approved without interview.

One lawyer puts it something like 'if you don't have anything else, bring affidavits'.

To answer your question here: If you want to find this information, you can find the requirements for affidavits at uscis.gov in the Removing Conditions pages.