Thank you for your question. To implement Visa Direct APIs, please review the Visa Direct documentation via this link - https://developer.visa.com/capabilities/visa_direct/docs and, in particular, see the top few paragraphs shaded in yellow that discuss the requirements to use Visa Direct.
After reading the documentation, if you meet those requirements, please click through the link in those paragraphs to the Visa Direct Program Implementation Questionnaire, fill it out, and submit to the email address listed on that form.
For Visa Direct mVisa chargeback information, please navigate to Visa Direct API Reference and go to Reports API. You can find information on chargebacks.