Sounds like a genuine buyer. The NSW department doesn't require full details such as address, but others such as Victoria do. I'm based in Victoria and greatly dislike that to buy or sell from folks interstate (or others within Victoria for that matter) I need all their personal details, but the Victorian system absolutely requires it.
To pay you all he needs is your BSB and ACC number, and there's nothing particularly dangerous about that - all he can do with it is send you money or potentially see that it's the same account you've used for something else in the extremely unlikely event that he already has access to another transaction your account has been involved in, but in that case he already has your bank details and can't do anything more with having them again. I'll gladly post my bank details publicly if you like - it's not secret information.
When dealing with people in NSW I sometimes have this hesitance to give me their full address because the NSW rules don't require it. I honestly don't want their address but the Victorian department won't give me an export permit without it. Victoria and QLD are two of the slowest states in terms of updating their systems in a sensible way. Victoria still doesn't even allow for us to apply for permits online! We really shouldn't need anything more than a name and license number and the state systems should be able to look other details up without the buyer/seller needing access to it, but that's unfortunately how it currently is.
Though I don't know who it is etc and can't vouch for him, this guy sounds completely reasonable and not at all like a scammer, he's just doing what a legitimate buyer would and what people in QLD who buy from me do.
