I don't have much in the way of actual media to share with you, but I can definitely answer the second part of your question regarding relations in general between Germany's immediate allies...

EDIT: I'm not sure why, but someone's response with actual media was deleted...

When it comes to the immediate Allies of Germany; ones who could provide, or be provided with immediate and direct military aid, the opinions between were often variable. The Germans tended to have a casual arrogance towards any nation whose 'fighting prowess' did not seem to match their own; despite shared philosophies or political systems, and regardless of that nation's industrial capacity. It appears the Germans held the Finnish in perhaps the highest regard; and the common cause, especially for Balkan satellites, appeared to be the threat of Communism.

The relationship between Hitler and Marshal Antenoescu for example was gruff but amiable, but in no way, shape, or form often translate to respect between Romanian or German troops. Germans derided the larger part of the Romanian's ability to fight (despite recognizing an excellent tradition of mountain warfare) and how the Officers treated their men. There was without a doubt a shared philosophy in their atavastic fear of Bolshevism however - and that is something that extended to other countries in the Axis sphere of influence, such as Hungary. Again though, the relative accord between dictators did not always extend all the way 'to the ground' so to speak. Again using Romania as an example - there was absolutely an effort to build a camaraderie between at least the soldiers. Animosity between Romanian and German soldiers became so disastrous on the Ost Front that the Germans had to issue general orders for dealing with Romanian troops, and Marshal Antonescu suggested and implemented frequent banquets and inter-unit parties/lunches for neighboring German and Romanian units.

Returning to my preamble; Rommel regarded the Italian infantryman as a staunch defender if well led; and took great issue with the majority of Italian ground leadership. His nominal superior, for example, Marshal Bastico, was reputedly referred to as "Bombastico" by Rommel. This level of casual derision can be seen even in higher echelons of Nazi power; indeed it seems Hitler valued and rated his Italian counterpart's ability to wage war and lead a nation as very low indeed; an opinion no doubt formed during the debacles on the Albanian front in Greece.

Sources: "Staligrad: The Fateful Siege" Beevor, Antony

"Crete: Battle and Resistance" Beevor, Antony

"Rommel's North African Campaign" Massignani, Alessandro + Greene, Jacke

"Gazala 1942" Ford, Ken

Addenum: I highly recommend a reading of Massignani and Greene's book, its beginning to show its age, but it captures strategic and political interactions between German and Italian Generals, as well as their dictators, to some extent. More importantly it reflects the attitude Germany often had towards its erstwhile allies.