yes as they are both very reactive elements.
yes because magnesium is higher on the reactivity scale than iron
Yes. They do. Magnesium displaces copper from copper sulphate and forms magnesium sulphate and copper is separated as a solid.
This is a redox question. In order for Mg2+ to oxidize Fe(s), Mg2+ needs to have a higher reduction potential (tendency to be reduced) than Fe2+. Mg2+ + 2 e− --> Mg(s) E° = −2.372 VoltsFe2+...
Go find out for yourself.