Is it necessary that the person applying for the visa,
goes to the visa office, or can I send someone else
to the embassy with the HRDC and a copy of the job validation?

Applications can be submitted by correspondence (i.e., mail or courier).

If the case is being presented in person, the applicant would be best to present it him or herself. If an interview is requested in any case, then the applicant would need to attend such at the visa office to which the case is submitted.