Answer: Italian cypress are relatively clean, but over the years they will shed their inner needles so there will be some litter. The roots generally won't interfere with an in-ground pool. How close you plant them depends upon their mature width. If you stick with the narrow, upright varieties (var. sempervirens: also called 'fastigiata', 'stricta', and 'pyramidalis' which are columnar or narrowly conical), you can plant them 3-4' apart for a dense privacy screen.
Best wishes with your landscape!
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