point #1 is well covered in these forums so i'll not touch on it.

regarding point #2: unless your starting island is TRULY tiny (very rare but it does happen) then you will never want for copper, even on a 10 person server. each node goes quite deep. Iron is a bit of a different story but there's still enough on one map for everybody. Also, many large groups use "resource servers" which is just another map that everyone gets their mats from. this is done so that the map everyone is building on doesn't look like it was eaten by termites.