You can either create a route manually in Menu/Navigation/Competition task, adding one by one the different turnpoints you want to follow, or create a route easily on a webpage (on a map) and then transfer it to AIR³/XCTrack through QR code. Watch the tuto video related to that topic in the Videos tuto page. The Read more about Create a route/flight plan/task[…]
Yes, AIR³ is also a flight computer that computes all the info required to optimize your flight during competition. With a version of XCTrack > 0.6, AIR³ generates an IGC file that corresponds to the FAI standards and therefore belongs to the instrument accepted for FAI category 1 competitions. See XCTrack in the list of Read more about Is AIR³ ideal for competition?[…]
Yes. AIR³ is using a performing barometer sensor from Te connectivity to determine the altitude and the altitude changes. It can detect an altitude change of less than 10 cm per second.