It's a great tool! The FORWARD= and UP= are coordinates as well but used only for static cams. That would be IS_FIXED= option. If you set that option to 0, it will make it like a regular type camera that follows a car. And setting it to 1, it will turn on FIXED or static camera which is just looking at a point on track while the cars pass by. First you position the camera on track and that would be with the POSITION= coordinates like the normal cam. Then you need to tell the camera where to look. It needs two points in space for that, one for FORWARD and one for UP. You can read all those coordinates from this Caminfo app and you can make both these types of cameras there of course.
SHADOW_SPLIT I tried before but without much change so I'm not using it and leaving it to default. Best to to use some default values from Kunos.
NEAR_PLANE and FAR_PLANE is best to use default values of 0.1 for near and let's say 5000 for far. The units for this are in meters. You should google to get a detailed explanation. Anyway it tells to the game engine (like a 3D window) what distances from the camera to render. Any object close to the camera that is closer than the NEAR_PLANE distance will not be rendered anymore. Same for objects farthest away from the camera, with the FAR_PLANE will not be rendered if they are farther away than the FAR_PLANE distance value.
DOF parameters are for Depth of field and focus, but I use just auto DOF (setting is DOF_MANUAL=0).