Question about domain forest creation

I have 6 locations throughout a town that are all connected with a 5Mbps fiber VLAN. They average about 60 users per location. I will be upgrading them to domains soon and I just have a few questions about setting up a forest.
I have never setup a forest before, so some clarification would be great.
1)Does the first server you setup need to be Primary DC (or is there a primary DC in a forest)?

2)do I need the enterprise edition for a forest?

3)What should I consider when planning on setting up the forest? Anyone have any tips or recommendations?