Just browsing around at this stage, but my personal opinion is that you keep things flexible with the group composition.
People tend to screw up when they make a large number of characters to start, so my suggestion would be.
Start with the first option with one group. And then have characters split off and join/form other factions as disagreement/events etc happen.
The last thing you want is someone to make three character and then quit after 2~3 pages of IC xD That'd probably be RP death.
My question is;
How many years has it been since the "Change"
And how essential will knowledge of Colorado (Or other locations) be?