I would like to confirm several things I have come across. Sorry for so many questions.

1- An applicant can choose to mark "Hispanic or Latino," but not provide a subcategory, correct?
2- If the answer to question 1 is yes, then on the demographic information addendum (DIA), is it correct to leave the box for "I do not wish to provide this information" blank? Even though they are not providing the subcategory information.
3-An applicant can choose to mark "Mexican," but not provide a main category, correct?
4- If the answer to question 3 is yes, then on the DIA, is it correct to leave the box for "I do not wish to provide this information" blank? Even though they are not providing the main category information.
5- If the answer to question 3 is yes, and this is a face to face interview, is the lender required to collect the main category based on visual observation? If so, how should the box for "I do not wish to provide this information" be marked.

and last...

Is the section on the DIA, for the information collected based on visual observation, supposed to be left blank if the application is anything other than face to face. Leaving blank seems contradictory to the code we are supposed to report.

As David Dickinson says, much of what you've asked about falls under the M.C. Hammer rule - "Can't Touch This". If the applicant provides information in any of the three sections (Race, Sex, Ethnicity) you use what they provided, period. Whether they checked a main category and no subcategory, checked a subcategory and no main category, checked multiple main or subcategories - whatever they provided is what you use. You would NEVER complete the "I do not wish to provide" box - only the applicant can do that. ONLYif they leave a section blank AND do not check the "I do not wish to provide" box and you have a face-to-face meeting prior to closing, would you complete anything based on visual observation and surname.

Different topic question on the Addendum.

Is there any guidance for any kind of borrower signatures or initials on this form? We are not finding any. And we are on the fence about requiring them or not. On one hand, if we do require them to sign or initial the addendum, and if its not required, then we could be backing ourselves into a corner if one is missed (since it doesn't have a signature line.). On the other hand, we don't require them to sign and its just a paper attached to the application with no borrower acknowledgement.
(Note: While not required, 99% of our initial applications are signed. Even when they are telephone or internet apps. When the LO sends out initial docs the borrower, the application is included and asked to sign.)

I would not add signature lines

If the applicant is not a natural person, we would code these fields as "not applicable". Does the same apply for the Visual Observation field or do we leave it blank for non-natural persons?

For Fields 31, 49, and 53, for a non-natural person applicant or borrower, you would code these with the appropriate numeric code for "Not Applicable". For fields 32, 49, and 54, if there is no co-applicant, you'd code these with the appropriate numeric code for "No co-applicant", If there is a non-natural person co-applicant, you'd code these with the appropriate numeric code for "Not Applicable". If there is a natural person co-applicant, you'd code either as "Collected on basis of visual observation or surname" or "Not collected on basis of visual observation or surname" as appropriate.

Thank you!