First of all, be sure what do you really want:
- Non-Dedicated server is more like regular game. As host you will able to get achievments, all the stuff will work the same way as single player. The only thing is different, is that the save system work with 1 slot, and its not able to save the current position on the level. It saves the game progress, the current level and players items and frags.
- Dedicated server is more like online game, where all the progress saves automatically. You're not able to load or save the game manually, like you can in the regular game. Some of game features are simplified for connection optimization, for example dead bodies, you cant move or damage them. All the players are able to save their items and frags all the time. More than that, players data saves automatically while traveling between levels. That means, you can join the server any time, and you will get all your items.

More information soon...