Yes. Presumably trained up by the same personnel who train CFAVs
VGS staff (of a certain category) can train PTT instructors. The training required is dependent on the trainees prior experience (i.e are they a current QGI who just needs to learn how to operate the PTT software or is it someone who needs to be taught the syllabus and patter along with PTT operation). The status (cadet or CFAV) being trained is largely irrelevant, the training will be amended to suit the candidate.
Yep. So a function of 2FTS.