All non-necro minions (Druid animals and faeries, Ranger animals, and 
Merchant guards) are all based on the same code.  As such you will have
a skill or a spell that will summon them and separate skill or spell that
will control them.  You can use the controlling skill/spell to give your 
minion a myriad of commands.  

Examples:
cast control minion at follow...........makes the minion follow you
cast control minion at unfollow.........makes the minion stop following
cast control minion at go ....makes the minion move 
cast control minion at kill ...makes your minion attack 
cast control minion at get all..........makes the minion get all on ground
cast control minion at drop all.........makes the minion drop all
cast control minion at dismiss..........makes the minion go away
cast control minion at  .makes the minion  to


Some minions can act as mounts and as such can do anything a mount can. 

Examples:
mount ...............allows you to ride 
pack all on .........allows you to pack your inventory on 
unpack all from .....unpacks everything you have packed

All minions work basically the same way in that you tank for them, 
not the other way around. This means that the animal never takes melee 
damage until you are dead.  Then and only then will they take melee damage.

The advantage is you have a continuous physical attack going off 
every round through the minion,  as well as any spells or skills the minion
might 
have. But you still take all the damage.  

Minions will work in a party even if you are not in the front row. Of
course 
when you face an aggressive monster the minion enters first and thus gets 
hit first.  That means you'd better be able to soak one round of combat 
yourself if you use them.  After that, the tank will most likely take
damage 
like in a normal party.  However occasionally the monsters will target the 
minion and thus you will get hit again.  When a spell goes off, like an
area spell or a spell targeted at the animal, it is not the tank that takes
the damage, but the animal, so there is some risk in using animals in a
party.
Then again, any little extra bit of damage helps and the animals make 
such a convenient companion that many consider extra danger to themselves
to 
be worth it to have them around.  If you should happen to get your minion 
killed however, you will suffer a penalty, usually in experience points.
It's not 
nearly as much as it would cost you if you were to actually die.