You do not need specific SQF Training to be a Practitioner. You only need to complete a HACCP Training Course, show that you are knowledgeable in SQF Code, and proficient in implementing the food safety system. I completed my certificated training for SQF (Practitioner & Internal Auditing) some years ago when this was relevant in the code (7.1 I think). I do find training very helpful and encourage all to take up more training to increase the knowledge base so retaking may be useful to you.
Here is the code reference:
188.8.131.52 Senior site management shall designate an SQF practitioner for each site with responsibility and authority to:
i. Oversee the development, implementation, review and maintenance of the SQF System, including food safety fundamentals outlined in 2.4.2, and the food safety plan outlined in 2.4.3.
ii. Take appropriate action to ensure the integrity of the SQF System; and
iii. Communicate to relevant personnel all information essential to ensure the effective implementation and maintenance of the SQF System.
184.108.40.206 The SQF practitioner shall:
i. Be employed by the site as a company employee on a full-time basis;
ii. Hold a position of responsibility in relation to the management of the site's SQF System;
iii. Have completed a HACCP training course;
iv. Be competent to implement and maintain HACCP based food safety plans; and
v. Have an understanding of the SQF Food Safety Code for Manufacturing and the requirements to implement and maintain an SQF System relevant to the site's scope of certification.
I cannot speak on the extending the audit date as I have not undertaken this request.
Hope this helps.