..wut?
Equi, could you link your armory page, since.. you're definately doing something wrong - no offense.
1. Personally I use dispel glyph [likely change it to something else after nerf], FH glyph is a must and PWS glyph is highly desired for a discipline priest. Dispel glyph, especially after nerf, can be argued to be changed to pretty much anything.
2. Some do use, personally I consider it as a waste of mana, only using it if I know I'll be unable to heal for a period of time [..Maexxna's web wrap, for example]. It kinda works as a buffer and fits to discipline. Unfortunately Rapture doesen't return mana from it, nor can it crit to provide DA. Usually it's just overheal every 3 secs, so..
3. Every 10 secs, unless it's about to bounce more with it's existing charges.
4. Keep PWS up, preshielding can be done, altough some argue against it for druid/warrior tanks. Definately preshield tankadins & DK's though. Definately, after some rage has been gathered PWS. In heroics I usually pom, wait for it to bounce, PWS. Once shield has worn off, pom is already off from cd.
Penance is your main actual heal, and flash heal when you can't do either Penance nor PWS. Personally I ignore HN, but I heard it's very neat. PoH is good groupheal, and I'd like to add Divine Hymn as amazing group heal. Downside of the later is 6 min cd. If you are using Divine Hymn in heroics, avoid giving pain suppression to trash. Bosses are most likely immune, so far haven't found any that would get incapacitated, and therefore gain -40% dmg taken.
5. It's okay, few chances I'd do:
http://www.wowhead.com/?talent=bVcbuhxtMxoifRt0xtc
Healing focus is unneeded for PvE. You get rarely interrupted, Penance always gets one tick off from it whetever it is 0/2 or 2/2, PWS/pom are both instants, therefore unaffected. But like said, you rarely get interrupted at all. Max out Enlightement. While 1% spirit/stam/haste isn't much, it's nice add. And there is nothing more useful for you either.
Equi: Um.. Why you have so much oo5sr regen? And how can you run oom? Oo5sr regen is not needed, since you shouldn't be sitting out doing nothing as disc. Personally atm I have 639 and I'm still reducing the amount of spirit I have [being ex-spiritwhore..] for better stats. Are you losing crit or spellpower in favor of that +spirit?
Greater heal & flash heal, glyphed in normal disc spec are practically equal in hpm, but flash heal has more chances of proccing DA and giving you more mana. Therefore you should ignore greater heal. -15% off from Penance is a joke by itself for the reason of penance being highly mana effective already. Improved healing does not improve flash heal or PWS, so you should drop those 3.
Why are you not specced for imp. Fortitude? And even more so, why have you specced Silent Resolve? Can see you skipping imp. Fort if you are guaranteed to have multiple priests in raid that have it, but there is no reason to pick up Silent Resolve.
Same goes to Improved DS. Any shaman. I repeat: ANY shaman in your raid will replace your buff. Not worth of two talent points, assuming your guild has any shamans.
And how on earth improving bubble is not worth it? I have a reason to suspect that my bubbles would be way less than 6k's if I would not have improved them. And by way less, I doubdt 1,2k-1,4k less would be enough. Borrowed Time is amazing talent, so is Imp. PWS [altough I have heard rumors of it's bugged status, anyone filling up that..?].
I really can't recall situation where I would've run oom.. most of the time I bring forth shadowfiend just for few extra hits on boss, not because I'd need mana.. And that's while Rapture/PWS combo is bugged, I'm really looking forward a way to burn my mana post-3.0.8, assuming they've fixed it.