Wow, boxing a pally healer.... You are brave my friend. I only play my pally as healer in raids when im not tanking, so i can swap my priest to shadow for dps. I use healbot personally, it works very well with paladins, given the lack of variety in healing spells for pallys. There's a lot of fights where the whole group takes damage, and there might not be time to heal everyone individually. Make sure you get the glyph of holy light, and use HL for "aoe" healing, its splash healing will help a bunch on fights like Drakkari Colossus. Also, dont forget to use judgement of light/wisdom, as it increases your haste, and therefore heals land quicker. Also, just because its a healer, doesnt mean it cant be used semi offensively. Paladins have a few tricks up their sleeves... near universal temporary CC with hammer, AoE undead stun helps a lot in Drak Tharon Keep. Bubble if you get aggro, etc etc. Just because you aren't a Disc priest doesn't mean you have to only be reactionary healing, be proactive, and try and prevent damage from happening in the first place. Just curious, but what's the rest of your team like?

Shaeman's method is a good one. You could also use IS boxer's mouse click passing, and use something like Grid, or healbot, and click heal it. Hell, you could probably just "drive" from the pally healer, and just use the tank as a "slave"

I would go with 2 basic macros, one that heals the healer, and if beacon is up on the tank, you always will be healing the tank anyway, and a direct heal on whoever has aggro, using targettarget. Maybe even bind that heal to a taunt on the target, so you will cast a pre emptive FoL on anyone who pulls aggro, or gets targeted by a boss with strange abilities (like instructor razuvious, he targets a random raid member, and chucks a knife at em, which does about 10k damage, and im sure there's other similar things that im not thinking about now.

That way you have a mindless "heal whoever probably needs it" button. Then for more focused healing, just use the target macros, and cast the heal of choice, from your massive list of 3 healing spells...

To target yourself, you have to use /targetplayer or /cast [target=player] the other targets are just like you said, /target party1 /target party2 etc etc. Note, that the order of party members is different on each toon, with the toon being party1 all the time, and usually party2 is the leader. You can also do it by name if you want to be absolutely sure.