You've already received a lot of useful info here. It's great that Sina has a grammar book as most people don't really know what the rules actually are! I'll add some examples to further clarify (or complicate) things for you.
As far as Sina's number 4 goes, note the difference between "Ne obraca se tebi" and "Ne obraca ti se". The second one is like "He's not talking to you" and the first "He's not talking to YOU".
Here are some examples for the word order, in approximate order of the most natural sounding first, as it would really depend on the context, what you are trying to emphasise:
Njega slusam svaki dan.
Slusam ga svaki dan.
Slusam njega svaki dan.
Svaki dan ga slusam.
Svaki dan njega slusam.
Svaki dan slusam njega.
Svaki dan slusam ga - INCORRECT (maybe you could get away with it in a poem)
Ga slusam svaki dan - INCORRECT
Every time you use "njega", the stress is on "njega" as the emphasis is on him. When you use "ga", you stress either the verb or in "slusam ga svaki dan" the adjective "svaki".
Q: Da li ga slusas? A: Slusam ga!
Q: Koga slusas? A: Slusam njega.