Hey all, our club will be running our first territory based campaign for 40k and are wondering what would be the best mapsize for a campaign of about 5-8 people playing?

Second of all I am trying to find a Hexmap creator program but there doesn't seem to be any free software that allows me to define the landtype and who is currently in control of said tile.

So two questions basically

Whats the best mapsize for 5-8 players (how many hexes)
Is there any free software that can help me create a map?