For my son, on the Gateway (part3), it say “previous grade for grade 6, 7”, so in your case, you have to submit whatever previous grade reports the schools ask for. And your school registrar should be the one sending the reports, not you submit it yourself.
And for current grade, the school only submitted the autumn term report.
For the principal/counselor recommendation, we were suggested by a family friend, who did the application before, that we should ask the academic head of year group, rather than the principal, and that was what we did – we are from the UK curriculum international school.