No, it isn't
For units, abilities etc. even the standalone mods use the World Editor, then the object data, triggers and such are exported and put in a custom mpq in order to start with every map and replace the normal ones (the object data should be exported in .slk format, and the triggers... in .j probably, I don't know how is that done in the world editor, but I'm sure that after searching a bit, you'll find out how)
For menu stuff, it depends on what do you want to do, if the menu structure stays the same, you can simply put the custom models/textures for it in the same path as the ones the menu screen ones (always in a custom mpq), if you want to change it, it's a more difficult task, but probably notepad + common sense should work fine.
Take a look on how did they (the ones of "Project Revolution") change these things by opening their MPQ, then all will be clearer (probably)
For opening the MPQs, Magos' Model Editor should suffice, when you have to create one, use
MPQ Master.
You can also use
MPQDraft on your MPQ to make it an exe file (an SEMPQ) that starts Warcraft with the custom resources in it, so you won't need to replace "War3patch.mpq" with yours anymore to make the mod work.
Sorry for not being helpful, but I have only some clues about these things.