How old are most volcanoes?
The age of a volcano varies greatly ! There are new ones being 'born' all the time - and there are some that have been erupting for hundreds of years.
Volcanoes don't draw lava. The Earth's Core is molten rocks and metals. As tectonic plates move the force old land down into the core where it melts and joins the other molten material and also creates openings that the pressure of the molten core escapes through. Those openings are volcanoes. Underwater volcanoes are the most common as that's where most fault lines lie.