Hot magma or lava.
Igneous rocks are those that have solidified from molten rock, such as pumice, granite, basalt, obsidian, rhyolite.
Igneous rock is volcanic. Earth had volcanoes - lots of volcanoes - long before it had appreciable water. Water is necessary for sedimentary rocks, and sedimentary rocks are necessary for metamorphic...
Yes. Because Igneous rocks were created before sedimentary and metamorphic rock.
Melting of the rock, then cooling and solidification of the magma or lava which contained it would result in the creation of igneous rock.