Hello, saw your project and the 2 attached images and I can assure you that I'm perfectly qualified for this job. I know I'm young but in my 2+ years as a Project Engineer I've performed the structural design for several types of structures, including a roughly 400 m long perimetral wall that I could show you if you´re interested, my experience also includes steel support structures, reinforced concrete buildings and both shallow and deep foundations. Apart from that, I'm skilled with construction drawings in AutoCAD as I would draw my own designs. Now for your questions:
1. As stated above, I was in charge of the design and drawing of a perimetral wall. I can show you the construction drawings if you'd like to look at them.
2. No real way of knowing beforehand, depends on the type of foundation, soil parameters, the loads that will be acting upon it and, in some cases, wind speeds in the zone of construction.
3. Basically what's stated above in Answer No. 2. And we'd obviously discuss the specific scope of the project.
4. From what I'm reading, you're asking for a structural design alongside a drawing, if that's the case then I should have it ready in 3-4 days. If I'm mistaken and it's only a drawing then it would take me 2 days max.
5. For design and drawing: $200
For drawing only: $120
Note: since you mentioned it, I am familiar with Australian guidelines.
Contact me for any doubts or questions you might have about myself or my experience. Hope to hear back!