From experience these are quite good engines , the cold start lumpiness could well be the engine temp sensor going , I had one that did the same thing , the management was seeing -32 at about +5 but as the temp built up it then started to act correctly , first thing to do is do a quick resistance check accross the temp sensor terminals , the -32 figure is default open circuit so should not change anything if you try and start it disconnected . The oil leak could be the cam carrier seal between head and carrier , or could be the injector pipes themselves , if it was the injector seal at its base you would hear a fluffing noise and carbon deposits around the top of the injector , you need to have a look closely and see exactly where the oil/diesel is coming from