yes, you can say that. It means that you will give thought to a specific point when forming an opinion on a broader subject. e.g. The judge took into consideration that the man was fearful for his own life when he acted violently.

Yes, you can certainly say that. An alternative phrase would be 'take into account' ('ter em conta' in Portuguese?).

I cant surely understand what you mean. When you have decision than someone gives advice to sharpen your decision. U can accept or u can decline proposal but u will surely use this advice. "Take into consideration" - u agreed with proposal and u will use it for making your decision.