henchmen questions

A few questions about henchmen on my team:

1. Can henchmen receive a morale boost if they are alive when a boss is killed?

2. I assume that the more henchmen on my team, the less exp I receive for a kill. Will I receive fewer exp if I also have non-henchmen on my team like Fire Imp, MOX, or a pet?

1 yes
2 yes on henchmen and mox and other such heroes, no on pets and the imp

If the character is under the Ally heading, they won't effect your experience, gold, or drops. If they are under your Party heading, they will.

Generally this, yes. However, if they are in party but FAR away (the name is grey instead of the standard white) then they do not reduce your drops/XP gain. This may seem like nit-picking, but something its useful to flag your party away so you can get the full XP, etc. instead of having to share it.

Additionally, its worth noting that in addition to heroes/henchmen being able to get morale boosts, they also acquire death penalty, making them weaker the more they die. There are also various consumables that can grant party wide morale boosts and remove DP from the entire party.

Okay, what about allies that are not officially part of my party, but just happen to be in the area where I'm battling foes.

Like those guards who patrol around nearby outposts. I'm battling some foes nearby, and the guards within aggro range join in. Will my exp be reduced if they attack my foes?

No, they will not effect you in any way

There is some affect, in that if you contribute very little to the kill you won't get XP or loot. Generally, if a mob is fighting an NPC try to get ~50% damage on it if you want loot.