NCERTs for history (old syllabus) amd geography (new syllabus) are a must specually for HPAS. Notes for history should be made as it becomes easy for last minute revision. geography revison will take only a day or two from ncert if you have spent good tym earlier on it. Specially for HPAS, HP gk is must as pattern has been changed this year and more weightage has been given to hp gk In mains too.
no,it is not necessary ,Don't go for ncert books .Go for books of good author.It is good if you want to crack IAS.But as per knowledge for HAS,no use.I met so many people who were selected but no body ever read ncert.So its up to u