For depreciation, it is usually best to get someone in to go in and evaluate your property and draw up a depreciation schedule for you (cost us about $600), unless you know what you are doing. They are worth paying for and most people will get at least the cost of doing so returned through tax in depreciation benefits.

As for the interest, your mortgage statement should have specified on it exactly how much of your repayments are interest, and how much is principle. If you cann't find it, a quick call to your home loan provider should be able to resolve this.