The correct answers to these open questions are the following.
1.- Were the Atlantic Revolutions justified? Did they promote the rights and freedoms they promised?
Yes, I consider that these Atlantic Revolutions were justified because people were sick and tired of the many aggravations and injustices committed by the European monarchies; it doesn't matter if these monarchies were the British monarchy, the Spanish monarchy, the French, or others.
In some ways, these revolutions promoted the rights and freedoms they promised. Not a hundred percent delivering of promises, but in many cases, yes. It all depends on what specific revolution we are talking about.
For instance, in the case of the Revolutionary War of Independence, the Continental Army victory against the English troops granted independence and the opportunity to create a new form of government that only benefitted the American people.
2.- Is violence always necessary in bringing about revolutionary change?
No, violence is not the only way. And to prove that, we have enough evidence of the case of Indian leader Mahatma Gandhi who decided for a non-violent approach to fight for the Independence of India from British rule.
3.- Were the Atlantic Revolutions worth the costs of blood and money?
As I said above, most of them yes. It all depends on the specific revolution. And the answer is yes because, at that time, the European monarchies were not going to easily give power away. Indeed no monarchies want to grant independence to their colonies, otherwise, the war would have not been an option. So the use of violence was the only way the people of that era had to get independence.