Form 3800 is about general business credit. The form itself includes multiple forms within it such as form 3468, 7207, 6765, 8881, and ect.  It is mentioned that the form is on the return of  1040, 1041, 1120, and 1065. 

I am curious about this form with the below questions:

1. How to fill in this form?

2. Where this form can be found on 1040?

3. Why this form is not included on 1120S return?