sjgIS350

In doing research into aftermarket wheel for my 06 IS350, I have found the following:

Fronts are 18 x 8 w 40mm offset
Rears are 18 x 8.5 w 45 mm offset

I don't plan on doing a plus 1 and want to stay with the same wheel size and offset as the factory wheels. Will also keep the same tire sizes.

So my questions are:

Has anybody found aftermakret wheels that have the exact same dimension and offset as the factory ones?

Most of the wheels I have seen don't have both 18 x8 and 18 x 8.5 available. Plus the offset is different.

How does going with different dimension/offset wheels affect the dynamics of the care (e.g. handling, tire wear, alignment, etc)?