And the longer version..!
1. Generally this has been the most prudent. It is not possible to know when the next bull, or bear, run will start, end, or do crazy things. You're not (I assume) an investment professional; and investment professionals get it wrong more often than not
2. What makes you think you know more than everyone else? IF you have really strong willpower, you can be a contrarian investor. It is safer to just buy what you can, when you can
3. This is all about having non-correlated asset classes. Bonds go up as stocks go down. If you rebalance twice a year, you get to sell high (yay!) and buy low (yay!!). "It may be that bonds are a bad buy right now" but people have been saying that for years (OTOH, if you can get something with a BETTER interest rate than a bond, but zero risk, take it - eg, your mortgage!!)
4. If you're buying the Australian index, aren't there a lot of miners in there already? IMHO - and it is just that - I'd buy a couple of thousand worth of precious metals just as a shit-hits-the-fan thing, for trading. Or, say, less than 5% of your portfolio.
5. You should be diverse, but as cheaply as possible. If you're already going to do stuff in US$, you might look at VXUS - which covers 'everything' except the US (I think it's something like 60% developed, 40% developing world). There is no point getting a fund that costs 1% just to add, say, Canada, if you already have Australia, the EU, the US and so on. 'Normal' percentages might be 20% Aus, 20% US, 20% rest-of-developed-world, 20% developing world, 20% bonds. Or if that's too complex - 30% home, 40% foreign, 30% bonds. Or 25% home, 35% foreign, 25% bonds, 5% precious metals, 10% REITs.
For 5, obviously you need to do some work to figure out where a) suits you best and b) is both tax and fee efficient.
Phew.