The rulebook and technical information on the USFSA website are not "for dummies" but they are accurate and understandable. Any other source is at serious risk of being out of date.
For your more specific question, spirals are not technical elements in prepre. They may contribute to the PCS, but that is up to the judge to decide. More generally, spirals never have levels, so their base value is always the same, and only the Judge's opinion, in the form of grade of execution, varies.
Personally I think backwards spirals are easier if the ice is not crowded.
(not a Judge)