Coilovers generally require an engineers certificate to demonstrate that they comply with the Australian Design Rules (ADR's) with regards to suspension travel, ride height, eyebrow height (the height from the centre of the hub to the top of the inner guard), and clearance from rubbing on full lock and full suspension travel. Height adjustable coilovers should be marked across the threads and spring perches so that an inspector (cops or rego) can identify if the heights been raised since the time of last rego inspection (to defect you!). My engineers cert was around $700, but i had a bigger suite of mods than you, think about getting one for peace of mind
All that being said it depends upon whether or not you need to be inspected upon transfer of registration or not. If you don't need a vehicle identity check then your mods won't be seen by the rego inspectors, and if you get a friendly local mechanic you should be alright. The cops around town are a mixed bag, and it depends on when and where you drive your liner and how you do so. What won't help is big chromies or a excessively loud exhaust.
Have no idea about Carbon Bonnets, but I imagine they'd be looking to see you have a 'secondary restraint' meaning that it takes two actions to open the bonnet, the pull cable in the cabin followed by the lifting the catch is ussually enough, if the catch is gone, then bonnet pins are OK (concealed type, not sharp protusion type). But as I said have no idea...
Worth considering also is that Teh Federal Department of Infrastructure and transport (forgotten what they're called these days) is looking at introducing a National Code of Pratice (NCOP) for light vehicle modifications.