Yes, if you are reasonably fit and you are keen enough to persist and learn. Like skiing, technique is a lot more important that brute strength.
No. Around 5 lessons should get you going with basic skills and another 5 to 10 sessions should see you going upwind. It can be difficult to schedule lessons though if the wind doesn't oblige. Flying a trainer kite will accelerate you learning. Go for it!
You experience the freedom of surfing without having to paddle out or wait for waves. You can fly like a glider without a hard landing. You get the speed of wakeboarding without needing a boat. You can travel long distances powered only by the wind. You can experience the thrill of carving and turning a board without travelling to the snow or risking gravel rash.
You can buy a complete set of secondhand gear (board, kite + bar, harness), depending on condition, anywhere from A$600 to A$2000. Price ranges for new gear are: Kite: A$900 to A$2000, Board: A$750 to A$1300, Harness: A$120 to A$250. Please note that if you are buying a second hand kite, make sure that the kite you are buying is less than 4 years old. Every year there are improvements in the safety of kites - by buying a relatively recent kite you will keep yourself safe. Never be tempted into buying a cheap old kite if you are a beginner - they are cheap for a reason and can be very
Your gear should last at least 3 to 5 years, barring major accidents such as kite tears. A lot of kite tears can be repaired however. You can patch small holes and tears yourself.