"But what I would like to know is what happens if this broker goes broke (pardon the pun) - what good are their guaranteed stop losses then?"
Did you ask that broker this question ? It seems to me you have been wondering out loud here instead of actually asking these brokers your questions. Like I said before, you should try to get direct answers from the horse's mouths.
Also, have a read of their PDS (Product Disclosure Statement), you will find answers to a lot of your questions there. Many newbies don't bother to read the PDS of their service provider, they should.
