Go to search tab here and type in what you want. There is so much information there. Only you know what you want and the path you can take. It's different for each person
DTV is a 5 year visa wait and see what happens in 5 years. Immagration can't ask for documents on arrival there are ti many people on this visa now it's multi entry so why would they ask it would take forever and who would carry all the documents.if you go to immagration for renew another 180 days you must show but border bounce no problem. It's not something anyone could predict and why would you worry about that.
You shouldn't have an issue in Australia The Thai consulate is very good. Just search here " DTV in Australia" there will be heaps of helpful posts explaining the process required to be successful in Australia
it's not immagration matter it's ministry of foreign affairs that you apply at the Thai consulate. Why is it a scam there have thousands of approvals already. You are just bitter because you were denied. First search in the box here for the embassy you applied. Then look at the documents that they supplied. Yours sounds like minimal documents ered submitted. Also you don't have to get notorized documents it's not necessary. It sounds like they check your documents and think your application is not genuine. Try again in different embassy using soft power. Try with Muay Thai company may cost a little more but you should be ok