There is no metal by the name 'thompson'.
Lutemium
Caesium (or cesium) is the softest metal.
yes it is
titanium
tungsten
metal
Chromium is the hardest metal; the Mohs hardness of osmium is 7 and the Mohs hardness of chromium is 8,5.
Diamond is the hardest substance known - but it is not a metal it is an arrangement of carbon atoms in a lattice.
diamond
nothing
No, I believe platinum is.
If you mean literally hard, then metal coins (found in many countries) would be the hardest.