try on resonance's website, answer key of set R is there.
Staedtler pencils are excellent. why you want to go for a different brand? any specific reason?
you can use the given 90 mins according to your wish. you can experience the interface of nata exam here https://g21.digialm.com//OnlineAssessment/[email protected]@M1
There are practice questions in the Mock Test Series - Section 2. There are 2 drawing questions in each section provided. Practice with the timer and submit your drawing to [email protected]. The faculty will give you feedback on your sketches with a relevant score.