It's been a year since I sat Higher English so my memory is a bit fuzzy, but I sat Ah the year just gone by and I thought I'd try my best to help...

The number of quotations is up in the air really; it's the way in which you analyse the quotes and references in your essay that will signify to a marker your understanding of the text. If you're writing about prose or drama you could get away with practically none and still get an A (not recommended but doable) - poetry wise I'd recommend a minimum of one quote per paragraph. It also depends on the essay you're writing. An essay on a play's key scene and it's impact on the narrative wouldn't require much quoting and the student could easily get away with just references, however, an essay on dramatic techniques such as lighting, or costume would probably benefit by having some specific quotations.
It's impossible to state an exact number really, as each person writes essays differently, and each essay will also require varying amounts of textual evidence to support its argument.

When revising texts I tend to do notes by themes on novels/ plays - writing the key events and key quotes for each one. For poems, I tend to just learn the poems in their entirety to the best of my capacity. Then when it comes to essay writing I'd just use as many quotes as I feel I need to in order to make a comprehensive argument. There isn't really a science to it, it's kind of just instinctual.

As for introductions and conclusions, they are there in order to establish what on earth you are talking about it, and to then sum it up in the end. A good introduction will introduce the text, perhaps some discussion of the plot, then will state what theme(s) you are going to discuss, as well as the literary techniques your analysis will focus on (NB. Use the words of the question!) . Conclusion-wise, bring together all the points you have made in your main body paragraphs and round it off with an evaluation.

A bad intro or conclusion won't completely damn your essay if your analysis is solid, but markers tend to look to them as a reflection of the quality of work in the main body. A crappy intro denotes a probably crappy main body, or a weak conclusion reflects a lacking argument.

Hope that helped :h: