Same here mostly, I have my "spam key" that every character has bound that I can spam in combat and be successful (Sinister Strike for rogue, Claw for druid, Sunder Armor for warrior, etc.) Other keys only have one or two characters with something bound to it. For example, I have three "spell interrupt" keys. One does earth shock, something fairly reliable and on a short cooldown and another has Hammer of Justice, potentially used for more then just spell interrupting. The third has Shield Bash and Kick on it, they are doubled up because often one or the other won't go off due to cooldown or lack of energy. This way if I press the key one, the other, or both (rarely) will go off.

For healing my primary character heals like normal, click heal then click a target while my other two characters have 5 heal keys each so they can quickly heal any target with a single keypress (at the cost of 10 action buttons). The reason I did this instead of focustarget is because focustarget takes a second to change on the remote client so my heals were always slow. Plus the main character would have to lose their target for a couple seconds anytime I wanted to heal with someone else which ended up causing problems in some scenarios.

I also have a generic follow key as well as 5 separate follow keys so I can either have the whole group follow (the norm) or just certain characters (for setup during some boss fights). I also have a key bound to turn right on all 5 characters which is what I use to stop following when needed (usually followed by one or more of the 5 follows to drop a character off).