Focus on target?

Okay so I decided I'd throw a noob question with maybe one not so noob.

1) What's the difference between target and focus and why do people perfer one over the other.

2)Is there a way to get your alts to look at a target...like say you're being attacked from behind..hit cast macro but have them turn towards the enemy?

3) Yes I only said two but this came up as I was typing....i've noticed that some macros have conditions with variables, how exactly does that all work out...like say using this macro, and if i understand it correctly i'm gonna use it up good

/cleartarget [noharm]
/cleartarget [dead]
/targetenemy [target=target,noexists]

Now in "/targetenemy[target=target,noexist] do the locations after your "=" pertain to a certain variable? Like...in the spot "noexist" is the only other option "exist" or are they just describing variables that you can throw in any order?

And finally can someone throw me a link to the different variables? Cause that would help out alot ;p I've looked...tho i'll admit not very hard...but hard enough for a not so hardcore multiboxer and haven't been able to find anything that gives out a list.

I will answer in reverse order, as the last one indirectlya nswers all of them.

Here is the Grail http://www.wowwiki.com/Making_a_macro use it wisely ;)

3. There are many options can be thrown together in any order (ish) there are too many to list here but the link above has them all.
Basic rule of thumb [1][2] = 1 or 2, [1,2] = 1 and 2; within certain parameters (eg reset) / = or so yor example could be rewritten

Code:

---

/cleartarget [noharm][dead]
 /targetenemy [target=target,noexists]

---

I think you may be able to do away with the target=target too

2. Not really, you could use a channeling spell like Drain Life to get them to turn to a target but this is the only way

1. There difference between target and focus is that by defaut spells will act upon the target if possible. you must explicitly specify focus as the recipient of a spell effect. There are default key bindings to set and change target.

Problem with Drain life and the like to turn you is that they need to already be facing the target enough to cast the spell in order for it to turn you.