Firstly, what does the report say specifically ie 1 in 100, 1 in 50,  1 in 10 year flood? This is how often you can expect innundation.
Secondly, you will find that you may have difficulty getting insurance, you must disclose the flooding issue with the prospective insurers. Speak to the town planners at council to understand more fully the effect of the flood notation – review their flood map, find out what mitigation works that the council has done or is planning to undertake.

Council also will give you a basic understanding of the effect of acid sulphate soils (or possibly a telephone call to a local geotech engineer).

Michael, as superhoops notes it is a very well positioned suburb on the lower north shore (abour 3-5 km from cbd). Prices aren't the cheapest around (even less so if it has any views).

If you aren't from Sydney, you'd probably be best advised to rent for 6 months to acquaint yourself with suitable areas (price isn't the only thing) – other areas may be better value or have a more suitable fit.

If pushing the dates back isn't an issue for you ie your finance approval still stands, you are requiring vp (no tenant) etc and you still have a roof over your head (or can extend your current occupation) would there be an issue? You may be able to argue a price reduction equivalent to the rent that they are recieving (and you would otherwise have recieved).

A couple of issues come to mind – firstly, what is your solicitor doing/advising?
Why does the banks valuer require access to the property? Vals for banks are usually done as 'drive-bys' ie external appraisal of the property – this confirms that the building exists (security for the lender), the state of the improvements and allows the valuer to prepare his valuation.
What is the difference between the settlement date and the vacation date for the tenants? ie is the premises being sold with vacant possession or with lease in place? Has the lease been terminated ie the tenants been given the appropriate notice in a timely fashion by the vendor/managing agent?
Why does the vendor require an extra month for settlement?
If the vendor is willing to recind the contract a) what penalties do you face b) do they have another higher offer in the wings?

Are back yard burn offs still legal in WA?

For $1k you'd get 3 men for a day plus rubbish removed – how many acres do you have?

It is all a matter of risk & how you undertake your due dilligence. I visit each area of interest, usually more than once (unless you rely on others to undertake this work).

Get to know the agents, the good, the bad & the ugly.

How will you know when you are being ripped off either on purchase price, rentals or repairs/refurbishment?

Is it possible to salary sacrifice sufficient to get to a lower tax threshold? – that way you are taxed on the cgt at the lower MRT (is this feasible or does any salary sacrifice get added back to your income for cgt assessment?)

Quit work (take a sabatical/unpaid leave etc to reduce your income)

Find a few capital losses to offset against the gain (you will need the losses in the same tax year although you can carry forward your losses indefinitely).

Intrinsically unless there are substantial differences between the units eg views (not availble from other units), additional common walls/ceilings, unit entitlements, traffic noise (internal roadway or main road), elevation, proximity to neighbours/lack of privacy issues then it would come down to your personal preferences.

The freestanding unit has its advantages – (point of difference): freestanding, can be treated like a villa or townhouse (or small house). This would be more the case if it had its own private courtyard on title.

Other units most likely all have at least one common wall (duplex/semi style), unless they are joined at the carport.

Unless the units are on a busy street, the better buy would be the front unit otherwise they would all be pretty equal in appeal.

Having said that, is there the opportunity to buy a pair of adjoining units and to consider combining the units at a later date to create a 3/1 combination or a 4 bed townhouse if the market dictates?

Alternatively are holiday lettings an option?

On the NSW contract for sale (2005) there is a box noting whether or not the following are applicable:
GST Y/N
Margin Scheme
Why GST is not applicable – Residential/Going Concern etc
Land Tax Recovery Y/N

Raising the land tax issue means may get reimbursed for some of what you have paid out (balance to end of calendar year) – this is perfectly legal to request & or reject. (If no-one queries it, then you will get reimbursed – as I am getting no benefit from paying someone else's land tax bill, I refuse to reimburse the vendor).

Your solicitor will ask for a Land Tax Clearance Certificate on the day of settlement to ensure that there is no land tax outstanding as at the day of settlement. In Tammy's case, it would seem like they had exchanged contracts and no Land Tax Clause was used.

I'd suggest researching the fringes of Blacktown/Toongabbie/Seven Hills/Winston Hills. The west has taken a battering over the past few years and presents reasonably good value (prices in the area need to catch up).  

Blacktown – has a railway station & busway/regional shopping centre & is between M4/M7/M2. Close to the industrial area, uni of Western Sydney
Toongabbie – has a railway station/new shopping centre (and more approved development above), handy to M2/M4
Seven Hills – has a railway station/Close to the industrial area/handy to M2
Winston Hills – proposed North West Railway (2017?), major shopping centre/handy to M2

The first 3 all have larger blocks, fibro houses, becoming an area with noticable migrant populations (renters), some areas have pockets of houses being redeveloped (slow change but a good sign of stability/improvement).