I’ll answer your question once one of you guys tries to answer the ones I posed.
Dio, your questions posed are just basic knowledge or comprehension i.e. not analysis, synthesis, or evaluation.
Let me help.
Main Point: What happened was that there was a civil war that broke out within a "wider war." i.e. WW2.
Tito was committed to the seizure of power at the war's end and a socialist revolution. On the other hand, Mihailovic was committed to the restoration of the royal and Serbian-dominated Yugoslavia.
Now, because Mihailovic was confronted by Communists he held talks with the Germans with a view of fighting against their common enemy. The Germans did not like this idea - but it is was the beginning of a relationship that played out across Yugoslavia. For example, in 1943, Tito's subordinates also had discussions with the Germans in Zagreb.
What's particulary important to consider is that despite Mihailovic's offer not to fight the Germans, they turned on him as well, most notably when Simovic (1942) was "declared" the commander of all Yugoslav forces: Note that the British also gave Simovic support as well.
I could certainly go on with this "mess", but what the heck, after all, it is (was) WW2.