Laptop request - AUSTRALIA, Budget < $1.4kAUD

LAPTOP QUESTIONNAIRE

• Total budget (in local currency) and country of purchase. Please do not use USD unless purchasing in the US: max budget $1.4kAUD, though I would be more inclined to spend <$1.3k.
• Are you open to refurbs/used? Yes but I just want it to be reliable because I have bought laptops on marketplace and they never seem to turn out well.
• How would you prioritize form factor (ultrabook, 2-in-1, etc.), build quality, performance, and battery life? Battery life is very important as it will mostly be used while travelling; I think reliability performance are probably also among my chief concerns, as I just basically want it to be able to work for the time that I need it to work, and to run my programs no problem.
• How important is weight and thinness to you? Relatively important, since I will be travelling on the train a lot and would like to use it while doing this. So, other things equal, lighter is better.
• Do you have a preferred screen size? If indifferent, put N/A. Bigger is better, but clarity is just as important since my eyesight is not the beeesssttt.
• Are you doing any CAD/video editing/photo editing/gaming? List which programs/games you desire to run. I'm an economist and will be using this laptop for running statistical software like Stata (I also use a bit of Python and R), for typesetting in LaTeX, for general research and for online meetings.
• If you're gaming, do you have certain games you want to play? At what settings and FPS do you want? N/A
• Any specific requirements such as good keyboard, reliable build quality, touch-screen, finger-print reader, optical drive or good input devices (keyboard/touchpad)? Ability to put a sim card in would be great, as like I mentioned I'll be on the train and will need internet and my phone is kind of a dumb phone; I don't care about touch screen/fingerprint reader; a decent camera would be nice; aux port for headphones also good;
• Leave any finishing thoughts here that you may feel are necessary and beneficial to the discussion. Basically I just want something that will do what I need and will be reliable for as long as possible. Also no Macs hehe. Thanks guys!!