MDL import

I have a lot of MDL objects.
1) Is there a way to import selecting them all (not one by one)?
2) Where is the best place/folder in ADE to put their textures?
3) How to get their thumbnails and save them in ADE?
Thanks a lot!
When I was making models back in FS2004 days, I would make several export groups. I had tons of tanks and hangers and buildings and cars and things. I think its like exporting an airplane. It has lots of parts also. Attaching parts that have the same materials takes away the issue of giant amounts of models. For instance, I could attach all the tanks as one single tank cluster (one part) and then I didnt have 50 or 100 Panzerkampfwagens to export.

Libraries might be the ultimate way to go. I have tried to do that. ORBX use this approach. (Im a plane maker.. Not good at advice for scenery making... sigh... ).
Put them in a library bgl file?
my target is P3D v4.
I placed all my MDL files in the folder \Airport Design Editor 176\P34\Models
It should be perfect if ADE would have for models the same feature it has to add objects in Library Object Manager in which you can add also folders of .bgl files and create their thumbnails.
I found a way to create thumbnails of MDL (one-by-one) but in Lists/Models menu there is no way to add a model with its thumbnail.
It would be wonderful to have such a feature.

I can see the MDL thumbnail only when I have added the model to the airport.
Its selection is in a blind way.
What a pity!

I hope I was clear enough to address you.