I am an Excel Guru, and I work for a major International retailer. In fact, the company is the parent company for Trade Secret, which I know is located in Australia.
It sounds like you will primarily need to use the Data Validation tool, and Conditional Formatting. I can set up a couple of simple tables that will allow you to create and edit lists that can then also appear as a drop down. I am happy to create those lists as well.
As I create your spreadsheet, I am also happy to include comments on how I did it so that you can be comfortable in knowing what to do if you need to change or edit the spreadsheet in any way.
I would love to work with you, and know that you would love my work!
Regards,
Trevor Smith