1. A Macro lens allows you to focus close to an object with a high level of magnification.
2. The lens attached to your camera. Seriously, practice with your kit lens first, if you keep encountering a block in focusing due to your lens' MFD, you can try a macro lens.
3. Depends on the scenery. I know most people are happy with the kit lens. Others buy an ultra-wide-angle lens. Others shoot scenery with a 300mm lens...
Yes... the 18-55mm kit lens can do that, but you would need an extra attachment...
Attachment can include,
1) Extension tube
2) Raynox closeup lens (250, 150), Canon's 500D, 250D (not to mistaken to the EOS 500D)
3) via an adapter - mount your 18-55mm reverse to your camera, or
4) via an adapter, mount another lens reverse to your 18-55mm