Stick, regarding exam timing, I think it'd be a good idea to stick to a maximum of 55 minutes per essay. That works out at 5 mins for the intro, 15 mins x 3 body paragraphs and 5 mins conclusion. Then you have a good 5 min allowance for proofreading time.
Having said this, you should all try to have the language analysis done as quick as possible, given that the quotes that you need are in front of you. All you need to practise and know is the structure and overall writing conventions for analysis. The other essays will be a bit trickier given that you need to memorise your quotes etc., so you might even need a bit more than 55 mins to write them.
Last thing - Stick, if you want to analyse multiple techniques together, choose the techniques carefully and you may be able to discuss the 'cumulative effect' of these examples, and how they work together to produce a larger effect on readers/listeners. Look at how the audience is positioned to think and feel. BUT, do not combine analyses too often in the essay, otherwise it'll be too broad. It is important to have a balance b/w broad and specific analysis.