If you want the texture to be completely on the stage then yes. Each one of those .pac's is for a different part of the stage. You don't necessarily have to have them all on. You can mix other textures together. If you are looking for the part you fight on though, that would be the one that says gdiff on it. Smashville is another stage that has multiple .pac files if you didn't know.
Not always. Spear Pillar has 3 (TENGAN1-3) But you can't just swap things between them. Some differently named stages don't always work over each other. Not even with rel files.