Seriously don't believe the rumours that people make.
They are not going to be true, unless it is by sheer luck.
If anything related to the question slipped out before the HSC date, there would be a massive scandal exposed about it in the Media, and BOS would start firing their staff.
They can't tell you what is in the question.
However that is not a trend for the last question to be on the last section of the syllabus - that is a definite. Every single teacher who teaching year 12 at my school is a HSC marker, and they have told us that it is always the case for Pompeii.
However as for the personalities and time, they keep stressing to us that question b does not have to be taken from the last section of the syllabus, it just tends to be because for 15 marks, they want more of a personalised opinion to show within your answer.
For Sparta, anything can be asked for the 15 marker. If it is something obscure, don't worry, because my teachers tell me they mark it less harshly in the marking centres, and they scale it up to allign with all the other ancient topics.
Just make sure you know you content really well, and just know a brief idea of what the historians of that topic focussed on in their writing.
That way, you can state historians said things about things, and markers will believe you if you correctly allign a historian to an idea that is of their view or way of thinking.