I bought the game from Insomnia sale and decided to try the game out.

I got to the tutorial, where you must do some attacking and stuff. First thing I noticed that tutorial tells me hit right mouse button to attack with my sword, when in reality I should press left mouse button to attack. Nothing serious, but still noticeable.

I got the part where I must throw bombs to those poles. How I should try to aim at them? I look at those two poles and throw the bomb, but Geralt decided to throw the bomb towards the old man automaticly. Should I select them as targets first and then throw? I couldn't figure this out and quit the game.

I decided to show to my friend the game and again, attacking showcases wrong button (the turorial message, not the UI on down left corner). I got to the part where I must strong attacks. I do the first attack and it connects. After that I couldn't even attack.

Is the tutorial buggy or am I doing something wrong here?

Probably you are doing some things wrong.

Attack is the right mouse button if you are counter-attacking, and you have to time it. If you are not counter-attacking it works as block in combat mode. And witcher sense in exploration mode.

Secondly if you press middle mouse button and hold it for a while it will go to manual aim mode. If it's press and instant release it's auto aim.

Well to be fair the key bindings are changeable, so it may be that your key bindings are not what was envisioned when the tutorial was written. I wouldn't worry about minor issues like that. Just remember which keys do what, and only take hints and tutorials at face value.