My Wheel Dilemma!

BGTV8

Camber in OEM is fixed, you can gain some camber by lowering with shorter springs otherwise you will need adjustable upper arms. There is a cheap solution and a "good" solution - I have the good solution (SPL) but there are cheaper solutions but you get what you pay for.

With more than 1.5 deg negative, unless your toe setting is spot on, you will risk feathering and additional wear in the inside edge of the tyre and shortened tyre life as a consequence. I run 2.0 - 2.5 neg and a titch of toe-in on the road and up to 4.5 camber and 2mm of toe-out on the track at the front, BUT I also have a hoist, setup plates, camber/caster gauge, scales and string lines on my setup pad in my man-cave so I don;t have to go to an alignment shop before and after each track day. I do know that if I DD the car with track settings I can chew out my dd tyres in a week to 10 days, so it is not something you want to do regularly if the Z is your DD

You are going to have to experiment a little I think

Tyres sizes front/rear need to be within ~2% OD.

255/35R19 is in the sweet spot for a 9.5" rim width and is around 660mm in diameter ...

For rears you'll need a tyre that is close in diameter, so maybe 295/30R18 is a good choice without going uber-wide and costing a motsa