Structure was essentially identical to the British table of organisation, except that in 1918 the infantry brigade retained four battalions whereas the British Army reduced to three per brigade. IIRC correctly there were some minor differences in artillery brigade structure. Bear in mind that attrition reduced numbers considerabLy from the paper strengths. This was particularly acute in the Australian Army which in the latter part of 1918 was forced to disband whole battalions to keep up strength in others. There is a fairly famous photograph from this period showing a platoon of less than 20 men but with a full complement of Lewis guns. So if you were to do two full strength sections you could have an actual strength platoon.
The official histories have a guide to the battalion patches. You can find all the Bean histories on the AWI website as well as a host of period photos. Nice thing is that it's a searchable database. Bloody awful reading Bean but perhaps not surprising from a jingo, yellow press journo.
Uniforms don't differ that much in detail, particularly in 28mm, from the British pattern and indeed due to supply issues British uniforms were frequently issued anyway.