- Edited
@Gourmet_DAO
For the third question.
For me, it is important to include the eye color, hair color, skin color shape of the face, habits and routines of the characters especially the important characters such as MCs or other character that can be seen in many chapters of your book.
Why? Because we are making a move! A literary art! Unlike mangas, comics and manhuas, our novel doesn't have illustrations. If we don't have illustrations our readers will only have a vague idea of our characters. It is important to let them imagine using the words and description you have given them. You might think that these were all pointless but in the readers' imagination, it is their fuel. It is the reason why they read.
Always remember that if you are writing, use your five sense. Hear, touch, smell, taste, and sight.
Always keep in mind that we need the readers to imagine what we are imagining the time we write. We are introducing them fictional characters, so we ought not to make them just 'fictional' but also relatable, that's why habits, beliefs and some other things were important too.
As for the room with guns hanging on the wall, it is part of what we call 'World-building' writing those simple descriptions will make your novel wven more immersive as if they were inside the novel itself.
Example: A room with a gun hanging on the wall. If you describe it like that, you can already tell the behavior of the owner of that room, maybe he's a hunter, a gun enthusiast or other related things.
Note: Even if something is not as important as you might think, it will surely pay-off in the long run. Even if some descriptions will not be seen in the future, still it is important in the present.