This question is a little different then the norm, but I am having trouble with castsequence macros that have not changed since BC, but now all of a sudden get stuck on the first spell in the sequence when my character changes directions in movement with instant cast spells, or begins movement after a spell is cast that has a cast time.

Is it just me?

The affliction thread has a pretty comprehensive analysis of DI and raid benefits ... I believe Shadowpriest + Affli Lock is currently the best DI combination. Balanced Drood is way down in 4th place for raid gains (although top for personal - that is the warlock's - dps gain).

When 4.1 comes out, Afflic locks drop Succu for Felhunter, right? If so, what do we replace the LoP glyph with?

What should the replacement be? For an Afflic lock, the only two I see that would be worth having are either:

A.) Glyph of Unstable Affliction

-or-

B.) Glyph of Bane of Agony

In terms of long fights, BoD will be more useful than BoA, so the extra time increase seems.. useless. And as for Unstable Affliction, the fifth of a second reduction be useful in casting a faster SB. So which should I choose for optimal DPS, or are they both user choice.

Bane of Agony will be your best bet....In decent raid gear you cast UA in close to or under a second anyway so it does you no good whatsoever to have the glyph.

Given that it takes 4951 Haste Rating* to get to ~50% passive haste for non-goblins and 4776 for goblins, it requires more than "decent" raid gear to get your unglyphed UA down to a 1 second cast time, let alone under 1 second.

With the glyph you'll still need 30% Haste which is 2589 or 2437 Haste Rating to GCD cap your UA, which is possible, but still more than the 372 profiles used in the Simcraft thread.

TL;DR: In current gear you don't need to worry about GCD capping your UA, with or without the glyph.

*From the affliction thread.

Will the glyphed Unending Breath increase swim speed in the Nefarian lava?

I was under the impression that since 4.x DoTs did update per tick.

"During Wrath of the Lich King, DoTs did not update on a per-tick basis with boss debuffs and it was much more beneficial to open a fight by applying these debuffs (Haunt, Shadow's Embrace and Improved Shadow Bolt) before applying DoTs, however in 4.0.1 this was changed so that DoTs damage would update on the fly with boss debuffs.

This means that it is no longer beneficial to delay applying our DoTs to get these debuffs up."

The above quote is from Jmickey's Affliction thread. Am I misunderstanding something here?

On an unrelated tangent, having browsed the official Blizzard forums, I am trying to figure out if the buff to Haunt will only apply to the Haunt cast spell damage, or if the buff coming in 4.1 will be a change to the damage modifier that Haunt does. If there clarification to this that I have so far overlooked?

How, if at all, are buffs (specifically Volcanic Potion and Heroism) applied to the Infernal and Doomguard? Are their stats updated as the warlock's stats increase or decrease? Or do they take a snapshot when summoned? Searching shows conflicting information.

I didn't go into very indepth testing on this, but I did some dummy Doomguard summons when I last wondered about it:
test1) "pop meta + SP trinket + bloodfury (orc sp) -> pop doomguard", fully clothed with ~20 haste, 17hit, some crit. - doomguard casts SB 3 seconds, each SB hits for ~12500k noncrit, no misses experienced. No change experienced after fading of cooldowns and meta.
test2) "pop doomguard -> wait 10 seconds -> pop meta + sp cooldowns" still fully clothed. Doomguard casts SB 3 seconds, each SB hits for ~10k noncrit, no misses experienced. No change experienced when the cooldowns were popped.
test3) "pop meta -> pop doomguard" still fully clothed. Doomguard casts SB 3 seconds, each SB hits for ~10k noncrit, no misses experienced. Metamorphosis had no effect on Doomguard's damage.
test4) "pop doomguard" while naked. 0% hit, 0% crit, 0% haste. Doomguard casts SB 3 seconds, each SB hits for around 2.5k noncrit, there were misses.

I know that basically this data was inconclusive to make sure following assumptions are pristine truth, but since testing doomguard is pretty painful with his cooldown, I accepted this to be generally acceptable.
Assumption 1) Doomguard snapshots stats on summon, and those stats do not change over the course of his existence (summon Doomguard where you have the most buffs, Meta not included. Most probably it just inherits your SP, not other damage buffs)
Assumption 2) Doomguard takes player's hit (or scales personal hit with player's hit to some extent)
Assumption 3) Doomguard does not take player's haste (unless there is some weird haste -> SP conversion.) The shadow bolt cast time is not affected by player's haste, when summoning. I am not sure if Bloodlust affects doomguard (if he was to be summoned before BL)

Answering your direct question: popping volcanic potion before doomguard will improve it's damage, after summoning doomguard will not alter his damage. Popping BL before doomguard will not affect him, if popping it after he is out will affect him or not - I don't know.

edit: So I just tested Timewarp with a help of a guildie. It does not affect Doomguard at all. No animation, no cast time change.

This is a question for destruction warlocks, do you have any recommendations for an addon that can make it easier to keep the soulfire buff up? Currently I use a SF mod that makes noises in combat when SF is about to expire or is not active, but this mod is terribly outdated and comes from the time when all specs had improved soulfire so it makes noises when Im affliction and you cant turn it off.

I need an addon for this, I cant manage the buff without some kind of reminder.

I use fortexorcist (with a lot of configuration).

Here's an example: Forte

My empty bars remain black and on the screen for 60 seconds. My soul fire buff is always towards the bottom so I can see the precise time remaining on the buff, and it turns black when it's empty. I've since removed the procs from forte since they give me too much clutter, but essentially it monitors my cooldowns, and dots on each target.