I do have a little bit of knowledge of doing animations in Blender for AC, so I'll give this a proper look later, but there are some driver animation experts floating around here.
Its greyed out because its parented to another empty further up. When you click on the greyed object, you'll see in the square highlight on the parents above where the item is now placed. But when it comes to the hand rotating past 90deg and leaving the wheel, you'll have to select animation at the top and reposition the bones at the specific keyframes needed.
Having a quite dabble with the file you sent, it does seem like you need to adjust the hand cube at a few keyframes like 13, so move the timeline to 13, move the cube where you want the hand to be and then press "I" and it'll save the new position of the hand at that keyframe (or whatever object you have selected at the time), then adjust the rest to suit. If you need another keyframe in between just move the timeline to that spot, adjust the hand and then press "I" again to add the new keyframe. But I generally find the less keyframes you can get away with the better and smoother the animation.
I believe your importer is messing you about here. 17kb is way too small for an fbx file track, and your tree structure within Blender seems very small. AC tracks need the roads, walls, pits, etc to be set as specific names (common example is 1ROAD, 1WALL, 1PIT, etc). These names correspond to the settings in the surfaces.ini file in the data folder of the track. You also need at least 1 pit box, start lines, etc, and I'm not sure the importer is doing this correct.
Try to download the trial of 3dSimEd, import the kn5 file into that (you should see the whole circuit), then export it from there using File->Plugin Export, the settings for AC at the bottom and change the FBX option to the top one). This will create an fbx file and texture folder, import the fbx file in blender, and this should have the textures assigned too. Then do what you want to do with the track and export the FBX. I use the following settings:
The error you are getting in KSeditor is because the texture gras-shad hasn't been assigned in kseditor. Go into materials, find the gras-shad material and assign the correct texture. However if you do the steps I mentioned above then kseditor usually finds all the textures correctly, the trick is to always have the Blender file and a folder called "texture" with it that contains all the textures the track uses. So long as you do that your life is a lot easier in kseditor.
