Firstly - welcome!
Land Titles offices don't get the sales information (and collect stamp duty etc) until settlement of a property sale which typically occurs 6 weeks after contract exchange (the initial sale). So the only way initial sales data can be collected immediately is via non compulsory reporting by real estate agents and so forth; this is what APM and REIV etc base there initial auction sales data on each weekend. 1 week later RP data report auction sales data which is meant to more accurate., but still not 100%.
A couple of months later we get the house price tracking stats from APM, RP-Data, Residex and finally the ABS - they are all based on actual government reported sales (via land titles registration), but each uses published but different statistical techniques in what they report.
In terms of technical analysis, many people do it, all the data providers mentioned provide both public and private (subscription only) reports for investors, R/E agents etc, but at the end of the day any forecast/prediction, just like for the stock market, is nothing more than someone's opinion, and no guarantee of future outcomes!
The best thing to remember about real estate is that all markets are local. DYOR in your target area if looking to buy or invest, and understand, the dynamics driving it, who is selling and who is buying and what the trends are and so on. Don't rely on newspaper articles, or internet forums etc to tell you what is going on
Cheers,
Beej