From my USA experience they have enough land leaders to cover all existing units at gamestart. What they would need is air leaders though, if you don't reorganize the air units you don't have enough leaders till 1938.
Vanilla should have a full set of generic images that are not replaced by a CORE install. Problem were the nation-specific ship images inserted by CORE as vanilla seldomly used nation-specific ones and relied on generic images instead.Note to Denniss:
During preparation work for an 0.70 installer I noticed that I am lacking some files you sent me (or uploaded?) in August 2014. Those were the model_*.bmp files with CORE specific names but vanilla images, that need to be installed in the vanilla structure so they display correctly when using vanilla on a CORE install. I have all the Nation specific ones, but not the generic ones.
Or are no generic files needed?