For finding Y+ values you need to use a calculator. I use THIS
if you are staying with just a rear wing sim, its small enough where you can simulate the viscous sub-layer, so shoot for a Y+ less then 1. If you plan on implementing a half car sim then go for the log-law region so that you wont have memory issues when applying your methodology to the whole car.
The max Non-ortho values you receive should be as low as possible. However, just the fact that there is a geometry in the domain means that the cells have to distort around it. This is normal and you will never get completely rid of non-ortho cells because your geometry is creating them. A max of 83 is fine, most of my meshes have 89 as its difficult to get every bad cell. Only when you have a lot of non-ortho cells or when a few are at 89.9 then you need to worry.
You can use the Mesh quality feature and set the iso volumes to show non-orthogonality. this will allow you to locate the bad cells and fix them in CAD with a chamfer or fillet. However, if the CAD changes effect the performance of your wing then you must either live with the non- ortho or try and remove them through the mesh settings. I have outlined a few of these topics in my article HERE