Does investing temporary essentia grant long-term benefits?

Question

There are a variety of ways to get temporary essentia points in Magic of Incarnum. Can these temporary essentia points be invested into things that last longer than the temporary essentia points themselves? Assuming they can be (and that needn't be true, but I can't find anything that says they can't), is it the process of having invested the points that makes the effect greater or is it the points staying invested that makes the effect greater?

Example

Arboc, a human Bbn1/Clr1 with the feats Cobalt Rage (MoI 37) and Divine Soultouch (MoI 37-8), takes a free action to spend a turn undead attempt to gain 1 point of temporary essentia and increase by 1 his essentia capacity in all soulmelds, incarnum feats, and other essentia-powered abilities. Arboc invests into the feat Cobalt Rage the 1 temporary essentia point and the 1 essentia point he got from the feat Cobalt Rage.

Having done this, what happens?

1. Arboc gains the benefit of having invested 2 points of essentia into his Cobalt Rage feat all day.
2. Arboc only gains the benefit of having 2 points of essentia into his feat Cobalt Rage for 1 round until the 1 point of temporary essentia disappears; afterward, he gains the benefit of having invested 1 point of essentia in the feat Cobalt Rage.

Answer 1

Here's the appropriate rules text.

In addition to soulmelds, you might have the ability to invest essentia into other receptacles, such as class and race abilities (a duskling’s speed bonus or an incandescent champion’s incandescent strike, for example) as well as certain spells and magic items. These receptacles are treated as soulmelds for the putpose of investing essentia into them, with one notable exception: Several feats described in Chapter 3 allow you to invest essentia into them. It is a particular quality of these feats that you must invest essentia into them at the start of the day, and that essentia remains invested in those feats for the entire day.

If a character loses essentia, this loss is deducted first from any noninvested essentia in the character’s pool. If this does not cover the entire loss, remove the invested essentia from a randomly determined soulmeld or other essentia investment. Continue until the entire loss has been accounted for. [pp50 MoI]

The only possible conflict is 'that essentia remains invested in those feats for the entire day' vs 'remove the invest essentia from randomly determined [...] or other essentia investment'. How can you remove it if it must remain invested?

This is trivially solved, however, by realizing that 'remains invested' is referring to the previous section talking about how a Incarnum-user can switch essentia between soulmelds, what action that takes, etc, and is simply noting that the feats work differently.

Ergo, once the Temporary essentia was lost, first any 'free' essentia would be removed, and if you had no free essentia, you would remove it randomly from essentia assigned to soulmelds or feats, breaking the regular usage of those feats under the specific > general ruling of RAW, as the section on specifically removing essentia specifies 'other receptacles' which includes feats, magic items (under the variant rule), some spells, class abilities, etc.

In the above example, Arboc the Clericbarian has only 2 essentia, both invested in his feat, when his temporary essentia is lost. So, with no other source of essentia to randomly determine where he loses things from, he would simply lose one of the invested essentia points in Cobalt Rage, leaving him with 1 point in Cobalt Rage. Without an ability that lets him reinvest essentia into cobalt rage, his Divine Soultouch feat is effectively useless - his Cobalt Rage feat can only have essentia invested in it 1/day, so using Divine Soultouch gives him an essentia and an increased capacity he has no use for.

Notably, if he had another point of Essentia from somewhere (perhaps being an Azurin?), he could use Divine Soultouch to increase his cap, place 2 essentia into Cobalt Rage(leaving 1 in his pool - 1 from cobalt rage feat, 1 from race, 1 from divine soultouch), and then when the 1 essentia from Divine Soultouch disappeared, it would disappear from the essentia pool rather than reducing his Cobalt Rage feat's invested essentia - leaving him with 2 essentia in cobalt rage all day long. This isn't a good use of feats, but it could still be done.

Note that none of this answers the Psycarnum Infusion + Azure Talent question, as Psycarnum Infusion has super weird 'counts as if it was full of essentia but isn't' wording that negates normal feat + essentia interactions.

Answer 2

Upon re-reading Magic of Incarnum in order to answer this question, I looked at the feats you showed, and then I looked for any rules regarding loss of Essentia. It turns out there is such a rule on page 50 of Magic of Incarnum in the 4th and final paragraph under the section titled Essentia, where it details what happens when Essentia is lost. Underneath that is a sub-section regarding Healing Essentia Damage, so there are obviously multiple ways by which Essentia points invested in the Cobalt Rage feat (among other things) might be lost.

Hope that helped!

Edit:

In Arboc's case, the temporary essentia point that is invested in the Cobalt Rage feat lasts one round, per the description of the Divine Soultouch feat. After the round is over, the temporary essentia disappears, and I would say that it does come straight from the Cobalt Rage feat (rather than randomly from any soulmelds or other feats, not that Arboc has anything else for it to come out from).