A question about DC UDF's (and some more).

Hi folks, a newbie asking for help .

I've been experimenting with DC, checking extra models and units, and realised that I had a UDF for the Italian Ariete Torpedo Boats that lacked depth charges. I thought it would be just a matter of "cut & paste" from the UDF of an Italian DD, for example, but it didn't work .

The question is: is there a tutorial (or something similar)somewhere about how to make/change UDF files?. I've found some things on mission editing, but not on ship-class creation.

Another question I'd like to ask. Some jrf models (not the originals, but downloaded ones) don't show on my DC ship-viewer. I mean, not in the class-list by countries, but on the 3D world. I use NDDBagley to quickly see models and decide if I will use them, but many of them just don't pop-up: I just get empty water.

Am I doing something wrong?. Will this models still work in the game? (I guess if they are released is because they work, right?).

Well, these games are excellent and should not be discountinued.