The marking scheme doesn't actually state a number of poems a candidate must reference in their answer. An examiner is look for answer with precise and accurate details on the selected poet that shows the candidate understands and has a good knowledge of the poet. Many students will write about three poems in their answer but it is well known that some students have got an A1 answer by using just one poem.
Well its always best to include at least 3 poems, 4 even would be more suited to Higher level, It shows the examiner you know youre poet and material. Quotes i would say at least 6 max 8 you dont need as much quotes so just remeber to always refer back to the question ! hope that helped x