@Caoimhin - not recommended as shows a bad grasp of Irish language thus give the examiner a bad impression before your have even begun your essay. However, marks ought not be deducted for doing so so if it is compulsory for you then you may do so a;though I would strongly not advocate it. If you must, plan quickly on a spider-diagram in English with a few key words or short sentences to translate
As regards the original post, 3 essays is a bare minimum although yes, I agree there is too much to be learning off by heart at this stage. My personal intention is to cover 6 essays and have paragraphs from each that may be applicable to any subject. As a passionate Irish speaker, I am lucky enough to feel confident in my grasp of the language to compose if need be and therefore I believe this will be sufficient. For revision, I'll glance over reamhfhocal and compound reamhfhocal and the genitive cases and the 5 different declensions of the Tuiseal Ginedach of the key phrases I intend on using.