AutoCAD Map 3D :: Drop Ortho-photo On Surface Generated From Contour Line - Multiple Association

I want to do a simple thing : drop ortho-photo on surface generated from contour line.

First thing, I need the basic terrain. I did import my contour line in a new draw, using the import map feature. I then saved the draw under the name " topo ". At this point, the contour line are 2D break line with no elevation.

I then opened a new draw to which I did associate my draw " topo ". Then I used a query to modify the elevation of the line using the attribute " contour " in my table, thus resulting in my breakline to become 3-D. It works fine. Then I save the new draw as " 3D_Topo ". I then get a warning :

" The association between objects interogated in the current drawing and associated will be deleted once the current document of the draw is closed " (I made the translation from french to english, in french it stated like this :  " L'association entre des objets interrogés dans des dessins courants et associés sera supprimée une fois le fichier de dessin courant fermé. " ). 

Well question #1 : What does this warning mean / imply ? 

Then, I have those .ecw files as ortho photo which I want to import. So I use the function " connect " with raster image, then I select my file, then I " add to draw ".... then something very strange happens. 

Sometime, the image appears correctly...and some other times I get nothing and I get this " disconnected " message in the task pane ..and no matter how many time I actually connect again the .ecw files, it will not happen in the draw ! Then I simply close the draw, start map 3D again, then I do the exact same thing, and sometime it works, sometime it doesn't. 

Question #2 : any clue on why the .ecw files sometime works, sometime doesn't? 

Now, let's assume I finally made it to connect correctly and that Map3d didn't crash whilst I was doing it (because I don't know for you, but here, it does happens quit often), I now have (as shows in the picture I attached) two thing. A surface made (well, I went back in the civil 3-D module to make the actual surface from the breakline definition) with the contour line and a imported image. I now want to drap the image on my surface! So I use the option " drap " which is in the surfaces option (in the ribbon surface tools)... well it looks nice since it propose me to use the surface I made up with the contour line as the base and the imported .ecw files as the file to be draped upon. So I simply do that and.... well...nothing happens! My image isn't draped at all, it stays there,  

Question #3 : How should I proceed to actually drap my image over my surface ? 

Question #4 : Considering I made it to drap the surface, how can I save this new draw independently of the attached other draw or database?