Let's see if I can help you:
1.The suspensions go white because your carbon tex files are in the wrong place. You can either put them inside your car folder or in a shared folder if you are using csm.
2.That happens because most 2010 cars come only in lod0, wich is the best level of detail. When the cars are at a distance, GP4 uses lower lods to keep PO low, and since your cars don't have those, they revert to the game original shapes. If you have a high end pc, using CSM you can chose to use lod 0 only. If your pc gets too slow, you'll need to download the lower lods from somewhere.
3. I use CSM to play, and in CSM the performance files go in a folder called, er, performance...
Hope I could help.