Is there freely available information which may answer these questions?
Definitely not for Australian Standards
Also wondering does the design require fuses or a circuit breaker?
It depends on what standard it falls under. If your device isn't an appliance it's probably going to fall under AS/NZS 3105, in which case if it has 3 or more GPOs a circuit breaker is required. To answer your other question, I've never seen a double pole relay required in the typical application of common product standards. There may be some obscure configurations that require it though. If you want to PM me more details I can give you some pointers as I'm very familiar with designing to AS/NZS 60335 and AS/NZS 3105.
I recommend not talking to a test lab first (here in Australia at least). They have a conflict of interest in that they want to do as much testing as possible to get the most money out of you. Contact a few electrical product certifiers. Unless it's something super standard they will each give you a different advice as to what standard to apply and even how they interpret the standard, so you then choose whichever one suits you best. Make sure you have anything they say in writing! If you're worried about how varied the answers you get from the certifiers are then contact the electrical safety office in your state and ask for their advice.
Your next step is to go and buy a copy of the standard. Note that this will probably require multiple purchases, as standards tend to reference other standards. The cost of standards is a rort and as protest I recommend you search for the standard on Baidu (the Chinese search engine) first and have a read of it before you go and buy a copy. Buying AS/NZS standards from Standards New Zealand is cheaper than from the Standards Australia cartel. If you need an IEC standard buy it from the Estonian Standards Institute for a sensible price.
I suspect the so-called "universal" outlet is not code-approved as a permanently installed device in any jurisdiction
In Australia I don't believe this is legal even on a plugged-in device unless it's specifically an international plug converter.
Ultimately, this is going to be an expensive exercise. There will be a small amount of overlap between requirements for the three markets you've mentioned but in reality you'll be basically doing separate testing for each one, at a cost of between $5k to $15k each (depending on the exact product requirements).