Your advice is really solid. One thing we've decided to do in our relationship is to give each other the freedom to express our true feelings and reaction so we can know each other better. Sometimes things get too bad, and we end up emotionally hurt. But we don't let it sleep with us. We discuss it after we are calm. Is this advisable to do so?
You should expect that two people, raised in two separate families, will at times have differences. Even two people in the same family will disagree with each other. The fact that a disagreement exists isn't the problem, it is how you go about coming to a resolution. Not letting a disagreement go unresolved for a long time is a proper plan. "'Be angry, and do not sin': do not let the sun go down on your wrath, nor give place to the devil" (Ephesians 4:26-27). Waiting a bit to calm down is an excellent step as well. "So then, my beloved brethren, let every man be swift to hear, slow to speak, slow to wrath; for the wrath of man does not produce the righteousness of God" (James 1:19-20). Too often, in the heat of anger, we are focused on winning our point and lose track of the fact that we should be searching out the truth and the best solution to a particular problem. It also means that neither one will always "win." No one is always right all the time.
Another thing that should be considered is that it isn't always best to say every little thing that comes to mind. We don't do this in society because it would be impolite. You don't tell everyone walking down the street exactly what you think of their waist size or style of dress. I'm sure you have your opinions on whether someone is too fat or dresses too poorly, but we understand that it is impolite to make mention of it. Now then, why would we treat our dearest companion with less respect?
"A fool vents all his feelings, but a wise man holds them back" (Proverbs 29:11).
"He who has knowledge spares his words, and a man of understanding is of a calm spirit. Even a fool is counted wise when he holds his peace; when he shuts his lips, he is considered perceptive" (Proverbs 17:27-28).
There are going to be times, despite your best effort, that you are going to injure your companion's feelings, but don't do so because you aren't thinking about how your words are going to be taken by the one you love. Too many people think being open and honest is permission to run a bulldozer over other people's feelings -- it isn't! "Let nothing be done through selfish ambition or conceit, but in lowliness of mind let each esteem others better than himself. Let each of you look out not only for his own interests, but also for the interests of others" (Philippians 2:3-4).
For more on improving your interpersonal skills, I would like you two to study, "The Ten Commandments on How to Get Along With Each Other."