Is there any way to import custom ships with scripting into this mod by working off of other ships models and scripting for a template?

So if I wanted to make an ISD with complete scripting, but just wanted to add a neat paint job to its texture file, what would be the best way to do that?

If I wanted to import a new custom mesh and use existing scripting to script a new fully working ship into the mod, is there any type of resource help on this topic?

While asking these questions I would also like to ask if it is okay to create assets and addons for this only for private use?

Thank you for your help.