Any type of volcano can produce basaltic lava. It is primarily associated with shield volcanoes, but it is also the primary lava produced by cinder cones. Stratovolcanoes are often associated with andesitic and rhyolitic lava, but they can produce basaltic lava.
No one knows exactly how much lava is in a volcano. It varies on the type or size of the volcano, as well as the intensity of the thermal forces within the volcano. Lava forms when heat (thermal force) acts upon rock, basically 'melting' the rock and creating lava.