Welcome..
Some points
Problem 1 - RA60 struts are known for positive camber. You can purchase strut tops from www.ajps.com.au to suit your Corolla but they won't help much if you are running standard style springs. The spring run into the side of the shock tower almost immediately. You really need to convert your struts to coil overs to get it working right - otomoto do a good kit. Or use different struts which don't cause the problem, like RT132 corona ones.
People often use a sigma lower control arm to sort out their camber issues. I believe the ball joint taper on the sigma arm doesn't match the toyota one, so some mods need doing if you want to go down that path.
Problem 2 - I think the RN25 Hilux diff is the perfect one in terms of size and correct stud pattern. It is also rare as rocking horse poop. I think that is why the Skyline one appeals, as it is correct stud pattern and LSD are easy enough to get.
Problem 4 - I know a good trimmer - Terry's Motor Trimming at Clayton. Its no where near where you are though :)
Good luck!