What would be the viewing distance and viewing angle or in other words would the LED panel be installed vertically ?
What are the viewing environment be dark and indoors or outside in bright daylight ?
It's a vertical installation, indoors with lights on. The viewing distance should be short, in the 6 feet (2 meters) range.
The thing is I can't rig the whole thing from scratch. I just don't have the knowledge, so I thought there might be a way to modify something already on the market, like the links I provided at the top. Time is not an issue, but this is a personal project and definitely I am not willing to spend thousands of dollars.
To maybe provide a better picture, imagine one of those old maps used to learn geography that had light bulbs on each state or country. A bulb comes on and you have to identify the location.
I need something similar, ideally with colors, and I thought it would be easier to control with a computer, as I would need to input individual addresses or a group of them, let's say I can turn on/off B23 or turn on/off B23, D18, G8, J15, A2.
Since you need them to be individually addressable, it's probably the same complexity as if you wanted to display an animation. Primary colors would make it 3 times as complex as a single color. To do any other colors other than R, G, B, white and black would make the project significantly more complex. This is probably not something that a novice is going to be able to accomplish. Very experienced people have made very small versions of what you're talking about and it was very difficult, time consuming, and expensive. Your project is easily in the thousands of dollar range and months worth of work, even if you knew what you were doing.
Why not first start with a blink sketch? Then toy with a port register, and then use two port registers in a matrix. Next, move to RGB LEDs and see if you can duplicate that same LED matrix in RGB. Finally, work on trying to control that RGB LED matrix to display exactly what you want. Once you get to this point, you'll probably see how unrealistic your project was. It's not impossible, just exceedingly complex, expensive, and time consuming. And really, you should master the blink sketch before you want to take on a project like this.