It is.

Lunar. You've got about a month where that's going to be relevant.

I did a search for this and didn't quite find what I was looking for, so I apologize if I just suck at searching.

In regard to spirit on our gear, is this not sub-optimal/wasted item budget? Obviously, spirit is .3 SP per point and other stats like haste or crit are in the .8 to .9 neighborhood. Obviously, it could also be the case that spirit is cheaper within the item budget and thus is perhaps not so bad.

I say this because I have been avoiding spirit-heavy gear, which had lead to be basically being unable to get the 4 piece bonus and instead wearing a lot of cloth (which is also very high in hit rating, making it further difficult to wear T8, hit-heavy as it is). Is this a mistake in gearing philosophy? Should I instead be going for leather? I should note that my guild is halfway through uld25 hardmodes, so ilvl 239 sp leather is starting to be very tempting.

1 Spirit costs the same as 1 hit/crit/haste rating. As a general matter, Spirit-bearing items are therefore suboptimal. But many are worth wearing due to sockets or 239 ilvl. You seem to have a sufficient understanding of the situation that you should just be doing actual numerical comparisons instead of looking for rules of thumb.

That seems a viable enough thing, but can't you pre-stack it before combat - I unfortunately haven't gotten lucky enough to get either - but i'm pretty sure it stacks off any healing spell and maybe thorns.

Illustration doesn't proc from thorns. You can just rejuv yourself 10 times and keep the stack up till you start combat easily.

I don't think very many people actually do this, unless they want to start combat down 6000 mana or waste a lot of time and food drinking for marginal benefit.

I personally don't do that, it's too much effort, I find my stacks getting up quick enough anyway from wrath spamming so I usually have 10 up by the time eclipse has procced. I try to keep the 10 stacks running mid combat say in Mimiron phases so I don't have to rebuild the stacks up and I'm regenning enough anyway.

Either way really, it's a small enough gain/loss that it could easily get overshadowed by rng. I honestly think i'll shoot for the Lunar first as well just to make use of the haste proc on my trinket since it'll likely proc around the same time as Lunar does.

With glyph of starfire, if starfire starts being cast right after at lets say a 2.1 casting speed and a roughly 1 seconds gcd, on the second starfire, would the 2nd 3 seconds bonus raise moonfires uptime to over 15 seconds or will it hit 15 seconds?

In other words, can glyph of starfire make moonfire's remaining time go over 15 seconds?

I know this issue is some days old, but the bonus of eclipse wrath is somewhat smaller as the multiplier is additive to the 10 % given by moonfury.

So without 2T8 its (1.1+0.3) / 1.1 which is actually only a 27.2% increase above your normal (moonfury powered) wrathes.
With 2t8 it gets up to (1.1+0.45)/1.1 which is a 40.9% increase over your normal wrathes.