Checklist Integration with DocuSign

We have a requirement to get digital signature on forms with prefilled candidate data using DocuSign. Each Candidate (Pending Worker) will have a separate form to sign.

We would like to have few clarifications on the subjected integration.

1) Do we need to manually upload document first to DocuSign and tag the same in checklist every time?

2) There are limited number of custom fields that are currently supported in DocuSign. But requirement is to get maximum fields auto populated based on candidate data.

Is there a better way to complete these activities. Are we missing on anything?