If you have 8 years of "reckonable residence" you can apply for "permission to remain without condition as to time". Processing time is a matter of a week or two.
If you have 5 years of "reckonable residence" you can apply for "long term residence", which is, in effect, a 5 year permit. Processing time is very long.
If you have 5 years of "reckonable residence" you can apply for "naturalisation", which means you will become an irish citizen (you can keep the aussie citizenship too). Processing time is very long.
In my view, you should apply for "long term residence", and at the same time apply for "naturalisation". You might choose to apply for "permission to remain without condition as to time" when you qualify for that.
Bear in mind that "reckonable residence" is calculated from GNIB stamps in your passport and from your GNIB card/Green Book record. You will need to keep your permission up to date while you wait for one of these.
Further (relatively limited) information can be found at:
http://www.inis.gov.ie/
Please feel free to ask more questions, we will try to help.
This is all to the best of my knowledge, people are welcome to correct any errors.