Purvikalyani is a well-known pratimadhyama janya raga derived from the 53rd Melakarta, Gamanashrama, not Kamavardhani.
Statement i: Correct – It uses prati madhyamam (M2).
Statement ii: Incorrect – The Arohana of Purvikalyani is linear: S R1 G3 M2 P D1 N3 S; there is no vakra in the ascent.
Statement iii: Correct – It uses Kaisiki Nishada (N3).
Statement iv: Incorrect – Purvikalyani is not derived from Kamavardhani (which is the 51st Melakarta), but from Gamanashrama (53rd).
Hence, the correct pair of statements is (i) and (iii).