Its part of the SSIP scheme. For sections which aren't relevant, eg asbestos, you can write a statement to this effect but consider all the potential scenario's eg if your employees are cleaning part of a building/inside which contains asbestos, could the equipment potentially knock it and damage it causing airbourne particles etc.
For assessing subcontractors, if you don't use them, write a statement to confirm this. If you do the easiest way is to compile a form to issue to subcontractors asking about their h&s arrangements, who the h&s contact is, copy of policy, accreditations, insurance, any enforcements etc. Get one to fill it out and use this as evidence. Also explain how you check work done by subbies. I know safe contractor has info sheets to help people complete the assessment. If you an internet search it should come up.
Hope this is helpful. Good luck.
Dawn