It's a shame coursework isn't worth more, at least we know where we stand with that and can redo it if necessary!
Unfortunately, I'm studying a different play and haven't read/ seen The Crucible so can't help you too much. However, I would recommend you see it performed/ a film version if one exists because I know sometimes when you read plays you don't immediately "get" them or enjoy them as much because they're not designed to be read per se and even if we do a class reading it's not the same because of course not everyone is a trained actor with perfect timing and the ability to master prosodic features. Also, we've been told to use our introduction for writing about context (i.e. how the chosen extract fits into the wider scheme of things, what's just happened before) and show the marker we know where we're going with the essay. In addition, every time you make a point try to say what the dramatic effect is.
I do like my teacher for this side of the course, but they are much better at the discussion side of English than they are at writing things down in essay format. They did give us a comparison grid thing but I don't find it very helpful because the headings basically just repeat what the question tells you to look at (context/ situation/ purpose, features of speech, form/structure (I guess speech features and form are a more elaborated version of "differences between talk in life and literature") and how attitudes and values are conveyed) and because a lot of them overlap it all gets terribly messy.
Before I tell you my personal strategy, I'd like to clarify the word "transcript" because I think we're using different definitions. In my mind, you don't compare transcripts with spontaneous speech per se because they both come under the heading of talk in life (and indeed, can sometimes be the same thing) and so both would always be compared with talk in literature.
In my introduction, I give a brief overview of two texts I am given and how they connect. This ideally should not be a repetition of what we're told by the exam paper, although you should use this information to guide your answer. I usually start with the common theme (e.g. Both texts concern a person seeking employment). Then (still in the introduction) I'd go on to discuss how the fact one is life and one is literature makes their purposes different. So... "As a transcript of spontaneous speech, everything said in A has a superficial, face value meaning whereas in B the speech is deliberately crafted so the author can express his distaste of the stigma surrounding lower classes". I might also point out broader differences and similarities between them, such as "Although both texts concern a job interview, A is ultimately more successful because the interviewer is more supportive and encouraging and the interviewee more assertive".
As with the food anthology, all of my points in the main body of my essay would ideally link back to stuff I've said in my introduction, but I would use quotes and find points of direct comparison. For example: Both interviewees hedge (quotes). However, whilst in A this is likely because of the spontaneous nature of the speaker's talk, in B the interviewee hedges because he feels nervous and uncomfortable. Although the focus should be on speech, I might briefly mention things like paralanguage or prose outside the text if relevant. For example, In B, the interviewee's working class background and lack of education is shown through his use of non standard grammar. This is reinforced by his shabby attire.
I'm bit sketchier on conclusion for this part. As they don't really matter much in the grand scheme of things, if I'm running out of time I tend to just scribble down a summary of similarities and differences. Or make a summary point about how everything I've pointed out helps each respective speaker achieve their purpose