The size of the wheel makes no difference, to keep the rolling circumference the tyre wall goes bigger or smaller, meaning both 18in and 19in will be the same size effectively once the tyre is fitted.
regarding the staggered fitment, 9.5 on the rear will be very close to the strut on the inside, not sure but you may need a spacer there as well to clear it. Also you will have to add some camber front and back to get them to fit under the arches, if you plan to lower it at all. And finally 19in 9.5j fake lm,s are going to weigh about the same as a R 32.
you will need a good stereo system pumped up loud so you cant here the crashing and banging from your set up.
Good luck post up pics of the car once there on.