For Healing:

Seriously consider Repeater Region based healing.
You can do that with Hot Key Net (which is free), while retaining Keyclone for your other boxing needs.

See this thread: http://www.dual-boxing.com/showthread.php?t=32741
In particular, Post #1 and #11.

If you go with Repeater Regions, you'll need a unit frame addon.
Something which you can get an alphabetical sort.
The top choices are:
a) Grid + Grid Custom Layouts + Clique
b) Healbot
c) Vuhdo

It comes down to a preference call, as far as appearance goes.
But they essentially do the same thing, as far as healing goes.
A given type of click, sends the desired heal to the target.



For DPS:

I like to have castsequences, for most of my toons.
If you are manually controlling the tank, consider placing key abilities on say 1-5.
And putting the same castsequence macro for all of your DPS on each of those keys.

If possible, I like to have one key where everyone will DPS.
And another where my healer is not DPS'ing, in case I need them free to heal.

Then have certain key abilities, maybe 0-4 per class, on their own keys.
Things like Heroism, Drop Totems, Battle Rez, etc.
But aside from these big guns, the more stuff you can automate by spamming fewer keys, the better.