They need to be a licensed RW tester, not all mechanics are. Depends on how good a friend your mechanic is as to how much other stuff they want to pick on as unRW. And there's usually at least one bush or bearing that needs to be replaced, sometimes it can be bad/expensive though with leaks and so forth.
Just get your car into a RW place asap so you have more time to fix the unRW items. You have 30 days from the date of the original inspection to clear everything or you have to pay another $50 RW inspection fee. Then take your RW notice to VICRoads and they will measure your exhaust clearance (don't go to Carlton). Maybe they'll have a look at your tyres but they shouldn't be looking under your bonnet etc caus you will already have a RW cert.
I went to Carlton for height and they were real pricks about it, I went somewhere else the same day after emptying the entire car and because it was about 2mins before closing he barely even looked before ripping off the sticker.
anything suspension related I recommend going to Centreline Suspension in Thomastown, but depends how far you want to travel.