I don't know if you have tried this, but you can add values to the Yes/No choices in the custom field and then use text mode to display them in a report. And you should also be able to create another calculated custom field that adds up that value to the responses to all the questions.
Here's the code to display the value in a project report. Just change the name of the field to the name of your custom field.
displayname=Yes/No (returns value)
linkedname=direct
namekey=Yes/No with Values
querysort=DE:Yes/No with Values
textmode=true
valueexpression={DE:Yes/No with Values}
valuefield=Yes/No with Values
valueformat=HTML