I think you are referring to clause 2.5.5 (?), "internal audits to verify the effectiveness of the SQF System".
>>>>Please read page #44 of the Mod 2 Guidance Doc.<<<<
There you will find all answers to your questions.
Q1 : "where possible to use personnel who are separate from the area being audited to conduct internal audits"; so yes you can audit your self, it's not recommended but it is accepted.
Q2: "This training need not be “formal” training provided by an external source. Internal auditor training covers internal audit procedures, including the planning and scheduling of internal audits, preparing internal audit reports and initiating and following up on audit findings. Internal audits should combine several information gathering techniques, including interview of personnel, review of records and observation of current conditions."
(you can train him with your experience and go trough the "ISO 19011 pdf" for example).
Q3: the audit include all, your procedures to ensure are up to date with what you are doing in the floor and what is happening in the production area.Go to the full post