Changing $this->template won't help at this point, since qa_content has already been created based on the current request.
$this->template == 'questions'; is equivalent to writing either:
true;
or
false;
depending on the value of $this->template, and is meaningless in terms of the running of the code (removing one = sign would help, but it still won't have an effect on qa_content).
What you need to do, I think, is to access the ^posts database directly, pull up a question, create an array, and pass it to qa_item_main();