Hi Hardik,
Check out Nokio's post on p22 of this thread - it covers most of your questions about Stage 1 including time limits and number of questions. It also has links to some more examples of cube questions, etc on the Psychometric Success website. You can buy books to cover these things on the same website but I don't know what they're like - I just made do with what I was sent by NATS and what I could find on the internet.
There isn't a separate maths paper - there's just a few maths questions (3-5 if I remember rightly) in the motivation paper in amongst the other NATS questions.
Any other questions, post back or PM me.
Jen