Do you think that the variation in plural forms (qdshym vs. qdshwt) is indicative of an actual gender distinction between temple prostitutes, or is this variation purely linguistic (as grammatical gender often does not correlate with sexual categories)?
The paradoxical gender/number agreements in Hebrew mostly concern adjectives in epithet, attributive or predicative functions (besides the specific case of the numerals). Here qadesh functions as a noun, and the masculine is likely inclusive (implying both male and female hierodules, possibly a majority of women) -- but a purely formal grammatical masculine for a 100 % female referrent is highly improbable. Afaik the qedeshim in Ugaritic texts are of both genders. The specific use of klb in Deuteronomy 23:19 (a title paralleled in other forms of Ashtarte/Aphrodite worship if I remember correctly) is another clue that male hierodules are involved too.
The polemical description of the bamoth (high places) sanctuaries as gab ("mound" or "booth" for "prostitution" = sex ritual), in Ezekiel 16:24,31,39 (cf. Jeremiah 3:2), on the other hand, involves a female character (cf. the famous "woman at the window" in Proverbs 7:6, a common motif in iconography).