Finance Question

I suggest that you mak ethe application BEFORE he returns to AU, that way he can prove his income from his present employer….hard but much easier than with no provable income or credit rating in AU.
As for using the entire nest egg in one basket…think again…see if you can buy several smaller investments properties using the min bank deposit….say 20% plus fees.
The banks will allow you to claim 70-80% of the other sources of income to pay off the debt but only allow you to use 30% of your current income. It also allows you to leverage the assets to a far greater extent.  ie: 20% of an average $400K investment property allows you to do the following: $80K plus 5% fees on $400K = $20K = $100K x 6 to 7 investment properties. This allows you to 'control' property worth 2.4 to 2.6 million. With an average 7% increase in each property valuation per year on the entire 2.4 to 2.6 mil = $168,000 to $182,000 increase in valuation. Use this increased equity as a 'deposit' on another investment property every 7-8 months. Let the rent pay off the loans as the valuation increases each year.
Start small, one to two properties to let the bank get used to the idea.
Do NOT buy the property you live in, rent it for 6 months, its cheaper than paying a mortgage and allows you to keep your investment cash in hand.
Do NOT be affraid of debt; debt allows you to leverage your cash at 5 to 1 (using a 20% deposit with an 80% mortgage).
Have your brother scout for additional properties that you can add value to: renovation or inprovements (car port, pario, add a bedroom internally). If you buy then rent a property every 6-8 weeks (at a min; more likely 12 to 16 weeks, you will have your 6 investment properties within 36 to 72 weeks AND you will have added value to every property as you renovate it before renting them out.
Make sure they are revalued every 6-12 months depending on the local market…this allows you to dip into the increased equity to buy another investment property.
Keep working and earning cash, the banks like that, while your brother cordinates the renovations, with your assistance on the weekends and nights.
Within 2 years, you should have at least 10 x $458K investment properties (7% increase x 2 years) = $4.58 MILLION under your control. Your debt should be approx 6 x $300K plus 1 x $332K (using a price increase of 4% every 6 months) plus 1 x $346K plus 1 x $360K plus 1 x $375K = $3.213 million. Thats a increase in valuation/net equity of $1.367 MILLION over 2 years. Not bad on an initial investment of $600K.
Thats a Cash-on-Cash return of 227%.   
Hope this starts you thinking BIGGER.
At the end of 2 years, all you wil be doing is buying investments properties and using the POSITIVE and PASSIVE income streams to live the high life. Best of luck.
 

I would advise people to be very careful when dealing with overseas "lenders". Often these "lenders" string people along with promises of finance. They collect all of your personal documents and then 'assess' you. You will nearly always be approved subject to paying a fee of some sort. Guess what happens when you pay the fee?

Then consider they have all your personal documents, including identity documents!

With such a high deposit, you could do Low-Doc, Rams is the leader in this market up to 80% LVR or go to one of the majors.  You will need to be referred to credit management to be approved.