Kakashi has done mistakes, that's true, but that's his way. Remember their first training, how hard it was and how he intimidated them? It's just his way.
As for Sasuke, it's normal to be closer to him. They were the only ones -at that point- with the sharingan except of Itachi aka their enemy! Who would be a better sensei for sasuke than Kakashi? It's logical to focus on him.
Also maybe being close to Naruto, hurts him alot. Naruto is the son of his dead sensei and a constant reminder of his comrade. Imagine that psychology?
And, just because it was mentioned, Naruto has self healing powers and Kakashi knew that. Sasuke on the other hand, the young genius with Konoha's secret weapon -Sharingan-, was running away. He thought of following him instead of helping Naruto, considering not only his student but also whole Konoha!