What are you trying to do?
Be a developer (business) or an investor?

If you are in business you need to have an ABN.  If your turnover is over $75,000 then you need to register for GST.  As you are selling a house that is more than $75,000 this is why you need to register for GST.  You can be a sole trader, partnership or a company.  If you are purchasing land and then putting a house on it (with a builder doing it) you also have to take into account the Land Margin Tax Scheme.  Upon completion of the property you sell it and then work out the GST. 

If you are an investor you don't need to have an ABN and upon completion of the property you keep it and rent it out.

Where is the development located? 

Are you intending on keeping or selling the properties upon completion?

Haven't used them.  Did a google search and they seem to be part of another company called Ascentiv Group.  Also, did an ASIC search on their name.  The business name has been registered since 14 Jan 2008.

It seems strange that you would be paying for a tenant's phone use, electricity and gas when you moved out of the property.  If you are paying for these they would be deductible.   If you are renting out the property then the rent and therefore any deductions should go at 21 Rent on the tax return, not at 24 Other Income.  Don't forget that you may also be claim for depreciation.  A quantity surveyor will be able to let you know if this is possible. 

If you get the information from the builder then I think the amount would be "builder costs" and not the cost that you would have to pay, i.e. retail should you need to replace anything.  The best approach is to get a depreciation report from a qualified quantity surveyor.  This way it's done right.

The ATO has put out some information regarding this.  Have a look at this article:  Has Your Rental Property been damaged or destroyed by a natural disaster?

http://www.ato.gov.au/content/00275211.htm

This should let some light on the subject for you.

The legal costs are considered a capital item so these are not expenses.  The borrowing costs are expensed over 5 years or the length of the loan whichever is the shortest.  They are pro-rata each year.  You will need to know the settlement date of the property and then the date when the property was available for rent.  You will only be able to claim the borrowing costs from when the propery was available for rent.  The other thing you may want to consider is obtaining a depreciation report.  And don't forget to advise the council that it is now an investment property as some councils have different rates for PPOR and investment properties. 

If you have purchased the investment properties in your own individual name (not sure about trusts, partnership, companies) then you may be able to re-allocate the depreciation which may give you more depreciation but there are rules that apply to this. <moderator: delete advertising>

The ATO produce a booklet Deductions for Prepaid Interest.  Link attached.

http://www.ato.gov.au/content/00270253.htm

I have designed my own spreadsheets that I use for my investment property bookkeeping business because I couldn't find any software that did what I wanted.  That is, work out my holding costs before tax, after tax, how much did the property cost me to buy, work out borrowing costs, re-allocate depreciation.  The spreadsheets calulate the holding costs for the total property, for each owner, and for my whole portfolio.  I have designed the spreadsheet so that they match the ATO's Rental Property Schedule – all the tax agent does it inputs the figures.  Too easy!