lower tempatures of melting in igneous rock effected by higher content of Al2O3, SiO2, H20 or Fe?

Answer 1

I think what you mean is what components have an effect on the melting point in igneous rocks. According to Bowen's Reaction Series, rocks rich in aluminum and iron tend to melt at higher temperatures whereas rocks rich in silicon melt at lower temperatures. Water tends to lower the melting point of rocks.