The spring rates you have are wrong to start with for a road car, so with 300lb rears, you can rest assured you will have oversteer (along with loose fillings etc) .

Ride height is dependent on type of rear beam and wheel size / tyres, so there is no hard and fast rule.

Also the geometry is decided by how you use the car and how you like to drive. Running big negative cambers will wear the tyres if used predominantly on the road.

Best thing to do is drive the car on standard settings and then report back as to what it does and what aspects you like and what you dislike. A plan of action can then be decided on how to fine tune the car to your driving style. However, you need to be honest about the way the car drives, as any advice I would give will be dependant on what you tell me....