It'll be fine. Might be easier to keep track of its location in the cellar though.

And to explain the angel's behaviour - monsters with standard AI don't drink or eat if they're satiated or if they don't use nutrition. Angels fall into the latter category.

My limbs get burned very rarely - most explosions I encounter either kill me or have no effect. I do get a lot of scars, however. The one time I had a stat reduction from burns, Seges was on my prayer list and I discovered naturally that she can heal burns. However, because burns are so rare for me, I thought that it was a scar caused by fire, and the lesson I took home was that Seges heals scars. Which she doesn't.

In conclusion, Seges healing burns is not excessively obscure - she's the only member of the pantheon I would expect that kind of effect from. What is obscure is the difference between burns and scars. One is visible on the character portrait, and the other can be healed by Seges? They should probably be merged.

I found an Atavus altar with a scroll of wishing in UT2 (or maybe 3) today, too! I'm saving it for later. Will probably use it for a socm or wand of cloning, but I have mirroring already.

It's a pretty natural way to program enemies with special abilities who aren't constrained by magic points. To use it every turn would be excessive. To use it on a regular schedule would require the monster to store extra information. Vanilla Angband monsters use this system too.
Of course a real Poisson process would have no lower bound on the minimum time between screams, nor would it have the screams restricted to the discrete moments when the enner beast gets a turn. A Poisson(-like) process would emerge as the continuous limit as the time between turns and the probability of screaming tends to 0.

Whether the enner beast screams on a given turn seems to be quite complex. Normally it has a one in 3 chance to scream, which approximately makes a Poisson process.
If it is panicked it won't scream, unless it's cornered, in which case it will scream every time it takes a turn. I haven't investigated IVAN's energy system, but it seems that the enner beast can take multiple actions (moving and screaming) on the same turn. Moving takes the standard 1000AP, but screaming takes 1,000,000 divided by its bite skill bonus. So if the bite bonus is not more than ~10,000, there should be a significant delay after each scream, making it not quite a Poisson process.
In summary, there's a minimum number of ticks between screams (which is more than the time it takes to move), and no maximum (but smaller delays are more likely than longer delays).
https://github.com/attnam/ivan/blob/master/Main/Source/human...

My understanding is that angels who appear when you make a sacrifice are permanent, whereas angels that appear when you pray are not.
Don't make them carry your stuff across the world map . >_<

The penguins could be useful if you want to get your intelligence down to 4 and become invisible to ESP. That might be more trouble than it's worth, though...

With a capitalist snowman friend?

As far as I can tell the slowed status on an item is permanent and doesn't stack, so it should be necessary to slow the ommel tooth plate more than once (unless someone casts haste on you).
How's your leg strength, and how much do you like your agi+dex scores? I'm going to include adamant (which is easily accessible through loricatus+food) in the following comparison:
Mithril plate armour reduces agi+dex by 10%, ommel tooth and adamant by 20%.
Mithril and ommel tooth plate armour together weigh the same as adamant.
Mithril provides just over 50% of the AV of Ommel tooth, which has about 7% more AV than adamant.
In other words, wearing ommel tooth and carrying mithril around as a backup is more or less equivalent to just wearing adamant, with the added hassle of worrying about when it'll spoil.
So the question boils down to: would you swap your mithril plate for adamantine plate? If so, then switch to the ommel tooth (and try to turn a spare plate armour into adamant before it spoils).