To answer the first question i think draco is so mean because 1. His father is a death eater and harry was the cause of lord voldemort's fall . That means in his household draco has grown to hate harry because his father hates him and 2. Draco is jealous of harry , harry gets alot of attention and draco would like to have the same attention that harry is getting.
I think draco is rude to ron once agin by draco's father Lucius malfoy hates the weasley's not only because they like muggles it's a feeling of superiority the weasley's are poor so they look down on them.
I think draco hates mudbloods because they feel that they are on the muggle side they are not fully witches and wisards .
I do not like malfoy not only because i like harry and he's mean to them .His personality and actions are very mean.

I do not think draco will be nice to anyharry ron or hermionee i sometimes think he will try to be nice to harry to get him away from ron and hermione like he did in the first book but he will have a stronger attempt . I do not think he will be on there side based on present events but he will actually contrube to a plot to hurt harry.