Ace_Boone,
It is actually quite simple with CFS2.
If you are talking about flying Missions with your friends, then yes, everyone will have to have the mission in order to see the same thing. They and you will also need a utilty call MultiSwap. This program allows you to swap to those missions for online flights together. Actually very simple to use and install. Not a big file. Correct name is MPSUtil 1.0. You will also need a small file to run MultiSwap, VB6 Runtime files. Get these here:
VB6 Runtime files....
http://www.flightsim.com/cgi/kds?$=main/filemust.htmMultiSwap.....
http://www.multicfs.com On the right side, click on CFS Utilities, in the drop down box of that page select CFS2. It will be the first download listed.
All your friends need these files and the mission file you want to fly together.
Now, whoever is hosting must run the Multiswap and and select the mission you want to fly and select your allegiance. Then the host fires up his game. Those that want to join should fire up there game, run the Multiswap and swap to the mission being flown, THEN enter IP of the Host and click join.
If you are all flying on the Zone, it works the same way. You MUST swap to the mission, run Multiswap, BEFORE you get into the game Ready Room or the mission won't swap.
Let me know if you or your friends need any more help.