latin
using textbooks to quote sources isn't the best thing to do, but really there isn't anything drastically wrong with it. When it comes to marking the HSC is the marker going to know exactly what text you used in class? The answer is No, for all they know you could have picked it up in your own time, for your own extra reading. Using some more "obscure" sources to supplement the bury and meiggs, hammond, kagan etc. would certainly add to your essay.
As to the quotes, surely remembering all your quotes wholesale is very impressive yet in recent times there has been a shift away from this. Paraphrasing may be slightly less brilliant yet if you can show a wide breadth of knowledge of both primary and secondary sources I am very confident that you will be fullfilling band 6 whether or not you quote directly or not.