1. Some classes allow for characters to have ‘helpers’ (i.e. familiars, animal companions, mounts). How do these differ from Cohorts? What about Improved Familiars or Mounts as Cohorts… or dire animal companions?
As stated these do not factor into the EL of the party. They are already considered a part of the class and factored into the EL of that class.
2. Are Cohorts, Animal Companions, Mounts, Familiars, Improved Familiars, Followers, etc. used to calculate average party level in regard to calculating an encounter’s CR and therefore total XP awarded?
No they are not calculated into it. The only of these that gain experience is the Cohort and he uses a specific calculation for that.
3. If they are included in the calculations, how are they computed? Are they another character or a percentage of a character (so a party of four with one cohort is 5 or 4+X)?
To determine how much XP a cohort gains. Take the xp the leader gets multiply it by the level of the cohort and then divide that total by the level of the leader.
Example: Leader is level 9, Cohort is level 7. Leader gains 500 xp. 500 x 7 = 3500, 3500/9 = 389. This is how much xp the cohort gets.
Note this is a bonus given out to pay toward the Cohort. The Leader does not split xp with the cohort. It is just a way to determine how much XP is going to the Cohort.
4. Can you give me some arguments for and against Cohorts (etc)? At this point I am personally leaning towards against them.
Cohorts can fulfill spots that the party is lacking. They gain only half a share of the parties treasure for the extra support they provide.
I myself play in a campaign where most of the group is melee based. So with Leadership Feat I took on a Cohort that is an archer type. This has helped the party by giving us someone who can covered aerial and long range support. I play him seperately even to the point of different accents (My character is more German, while the Cohort is French).
Mostly I suggest not allowing the Leader to use the Cohort as just a mule to carry stuff around. Defintely don't look at him as a way to help the Leader to make money either. The Cohort is a loyal follower who gains in ability, but is not a tool.
With careful play and even better roleplaying a Cohort can be a boon to a group. I would be careful to watch the player in his actions with the Cohort and if you feel he is not roleplaying it well then either control the Cohort yourself or don't allow it at all.
