#1 is just math.
If the origin of your minimap sprite is at the top left then a mouse click can be converted to layout coordinates with these expressions:
x:
lerp(0,LayoutWidth, unlerp(minimap.X, minimap.X+minimap.Width, Mouse.X))
y:
lerp(0,LayoutHeight, unlerp(minimap.Y, minimap.Y+minimap.Height, Mouse.Y))