(Game) Game Mode
: Private/Public/Automated Match Making.
Self-explanatory; You probably want to select "Public".
Leave it 'Unlocked'; Else, you'll force the Game Mode to stay as its actual value. For example, a locked "Private" would means no one would ever be able to play with someone he doesn't know which also implies a restricted spread of the map.->
(Game) Game Speed
You probably the "Faster" value on that one.
You probably want to 'Lock' it, but some might not want to.->
(Game) Locked Alliances
This one will really change on the situation. If you are making a Diplomacy map, you probably do not want to set it to 'Yes', but for "Impossible Scenarios" maps, you do want the 'Yes'. On that last case, you also want to 'Lock' it.->
: 1 Team/2 Teams/FFA/Custom teams.
This sets the number of teams that will be made in the lobby when you'll host. However, if not locked, the host can decide to alter them.->
I am not quite sure about all the values of this one.
Closed simply means the slots exists, but is blocked.
Open means anyone can fill the slot.
User, I think, implies that you invite someone to fill it.
Computer fills the slot with a computer.
You will not be able to set values for players that do not have Start Locations.->
(Player) Participant Role
Again, you will not be able to set values for players that do not have Start Locations.->
(Player) Team [2 Teams]
The values of this one depends on the number of players that have a Start Locations.
I've chosen "2 Teams" arbitrary: there are many others.
Here's a simple example that will make the explanations easier:
We see there are 4 players (all 'Open' slots => human players) that will be separated into 2 teams that aren't definitive (no 'Locked' value).
Let's analyze Player 3's value: "Team 2 ". This simply means the Player 3 will, by default (but not permanent), be the first player of the second team.
Therefore, "Team 3 " means that the player will be the second player of the 3rd team.