OK, attached is a prac report I did to show as an example to a Physics class I was teaching. It is not the best in the world because I whipped it up in half an hour.
However, it will give you a basic idea.
Prac reports also need a risk analysis (as stated in the post before). In Hypothesis you should add in some theory upon which you are basing your hypothesis. Discussion goes BEFORE conclusion. THe conclusion is a summary of what you have found and answers the aim.
Attached is also a prac report scaffold I took from a research paper.
AND about doing Senior Science and Physics - NO you can't. The Science Syllabus support document says (page 11) you can do EITHER Senior Science 2 Unit OR up to 6 units of Biology, Chem, Physics, Earth & Environment. If you do not want to carry on with the specific science in Year 12 you can transfer over to Senior Science. So, for example, say you do Chem and Phys in Prelim but only want to continue with Phys and not Chem. The Chem subject can become Senior Science and THEN in HSC year you can do Sen Sci and Phys.
Does that help?