Doing a quest with a group

I'm unclear about how the loot is divied up in a group quest. Sometimes I
get a message that my share of the money from a kill is X and other times I
don't. Sometimes the brown bag appears over a kill and I can right click on
it and get whatever is there and sometimes it isn't. Then other times, some
dice show up and we get to click on need or greed which is probably the
easiest to understand; it being a hierarcy/dice role division of what I
gather is rarer loot. But what about the money and the common stuff. How
is the division of that determined?

I believe that money is divided equally with all players regardless of
the looting option - which are Group Loot, Round Robin, Need Before
Greed, and Free for All.

These options are set by the party leader and you can view the option
by right clicking your portrait when in a party. This is how you
change it too.

The most common one is Group Loot. This works by allowing each member
to take turns looting the mobs. It's only active when you are near
each other though, so if you are other sides of the map you can loot
all of your kills.

Round Robin works like Group loot, but you take turns no matter what.

Need Before Greed works out whether you can use the item before letting
you loot it. I.e. an axe drops, the priest never sees it, but the
warrior loots it.

Free For All is just that. Anything killed can be looted by anyone.
This tends to get used when low levellers are grouped with high levels
as they couldn't care less about the sword with +1 stamina.

All of these options will bring up the Need/Greed dice window depending
on the threshold set. This is usually at green. So if a green item
drops, you get a chance to roll (but not in Need Before Greed if you
can't use the item and another member can.). This can be changed to
blue, purple or higher, so if you don't care about green drops, set it
to blue and the person who loots will keep any greens.

A final looting option is Master Looter. This is where the only person
who can loot is the Party Leader. He then gets the option to dish out
the item to any party member. This is generally used when the items at
stake are worth a lot or you don't trust each other It is always
used in high end raids (MC,ZG,AQ etc) and is generally combined with a
DKP system (Lots of info on the web about this) It also works with the
threshold.

It is one of the fairest looting structures I have seen in an MMORPG
and tends to work well when people's greed does not force them to click
Need on everything!