This my student is flying on my licence thing.... surely they are flying on their own medical certificate with your authority as their instructor, or are you merely highlighting how you personally perceive the situation in terms of your own conscience? Students do make mistakes when out solo and it's a rare scenario indeed where the instructor loses his licence over it. I only know one FI who allegedly lost his FI rating over a student error and that was only a rumour...
As for the above question - we don't teach spin recovery on a JAR PPL so it's not applicable as far as my job goes. I encourage solo PFL's in our training area, but not below 500ft. In fact solo PFL's are recommended where I work as a way of building solo time in the local area, as indeed are advanced turns. All exercises both dual and solo should be stated in the remarks section of the students logbook. As an aside here, when applying for an FI restriction removal the CAA like to see evidence of the applicant instructor having authorised a variety of different solo student exercises apart from the usual 12/13 and 18A.
VFE.