Hey Olgakoupt. Create a great material now, so that you can reuse it by creating instances of it. If you have many different materials it will slow down the game.
You don't make textures inside UE4, it's more the shader that you control. It's how the textures get used. For example; you wouldn't texture a crate inside UE4, but with careful planning you could control the tint of the crate in UE4, or create a switch to add or remove some decals you made for it.