LoS on Enemies, how do I improve AI? Pet dog AI help request

I have Line of Sight on enemy, but thats not good enough.

What I would like the enemies to do is sometimes look behind them, and flip/mirror the animation for a moment. How would I do this with even sheet?

I also created pet dog that follows player, but problem is that it goes trough walls. Is there anyway I could prevent this from happening?

You could try every X seconds : enemy set angle to 0(look right), assuming their current angle is 180(look left).

It goes through walls in what kind of game? If it's a top down game you can use Pathfinding instead and add the walls as obstacles. Find path to player, and it will go around the walls.