1&2 -- There may be something else you can do rather than have a tanking macro.

Are you using Keyclone? Have you considered making a keymap for your tank that will convert your primary tanking keys into the same hotkey string, and then have a keymap for your healer that converts that hotkey string into just the button for your healing macro?

I'm trying this on my 80 DK with two resto druids, and it was working pretty well in Outlands instances. All of my primary attack moves pump the castsequence macro on both druids, which cause them to spam the tank with HoTs. Direct heals I put on dedicated keys to call when needed. My macro for the healers looks something similar to....

/castsequence [target=focus] reset=7 Wild Growth, Rejuvenation, Lifebloom, Wild Growth, Lifebloom

I use the fact that Wild Growth has a cooldown control the macro and prevent too much clipping of the other HoTs.