After learning the fundamentals, should one start learning openings or should there be something else in between?
Moving from fundamentals to memorization of openings is probably not recommended. I would instead recommend learning the fundamentals of openings (controlling the center, developing minor pieces, don't bring out the queen too early (usually), pawn structure), and then, as you say in your comment, focusing on tactics practice.
If your goal is to play fast games, then studying openings is certainly going to help you increase the speed out of the gates.
If your goal is to improve your slow game, which is probably a good idea for most beginners: my recommendation is to consider each opening move as carefully as you would a move later in the game. Many openings are as tactically tricky as the middle game, so it pays to be careful.
Just my opinion. Obviously, there is a point where learning some openings will be helpful.
I believe studying the openings is a good way to go. Now, you don't want to memorize it. Instead find a book or some site that thoroughly analyzes the openings. Why?
You will learn of a way to approach a game with the type of style you prefer. Experimenting with different openings you get to learn more.
The opening is thoroughly studied and understood. Therefore, when you learn about each move, you will have in-depth knowledge where the 'whys' are completely explained. That way, you learn how much thought goes into each move, what is considered, how strategy is created and executed. When you play games with these openings yourself, you'll get the feel for its strengths and weaknesses.
Once you have learnt the moves of the game, in my opinion it's time to have some fun and start playing lots of games, gain some experience and catch the chess 'bug'!
A good way to do this would be to search online for your local chess club and go along a few times.
Once you have the 'bug', then you have more motivation for serious study later. In my opinion, in the early days, the best way to learn is to play lots of games, preferably against stronger players.
Try to be ego-less, you are likely to lose a lot of the time!
Keep a chess notebook with the score of the game and another page for notes where you record a single thing that you can learn from the played game. If there isn't anything obvious to you, see if you can get a stronger player to go through your game with you and suggest things that you could work on.
After learning fundamentals, learning "book" openings is a good way to add structure to your game. You have to start somewhere, and the opening is a good place to start.
JR Capablanca based his game on "fundamentals" and was ignorant of opening variations (for a Grandmaster), but he was a world champion.