That’s the same as you get with regular text. Read the online Help for how to thread text frames: https://helpx.adobe.com/indesign/using/threading-text.html

I guess it is failing for you because by default, GREP only works on single paragraps. You can force it to consider multi-paragraph matches by prepending the flag (?s) — this switches off “single line mode”.
Try something like this:

(?s)^<t>((?!\r<).)+

This should match any sequence of single characters (including hard returns) where “the next match” does not equal a hard return plus a new “<” start-of-next-tag marker.

You can apply your new paragraph styles this way, and in a second loop remove the ‘used’ <t> markers. I don’t think it’s safe to try both at the same time. Then again, from within a script this ought to be fast nevertheless.

> I know there is a preflight option to check for images that are not at their original proportions, but that?s not what I need.

Correct. “Proportions” don’t say anything about an image’s resolution.
The option that you DO need is under “IMAGES and OBJECTS”, “Image Resolution”, then check all three of Colour, Grayscale, and 1-bit Image Minimum resolution and fill in your preferred values.

> Oh yes, and am I right in assuming that just clicking the loaded cursor should place an image at 100% of its original size?

Yes, usually that’s the case. But at times I have found InDesign mis-reading the resolution information inside images, and, for example, got something interpreted as “1 dpi”. So suddenly an image placed at “100%” was 20 square meters large — according to InDesign.

If you are going to resize figures anyway, you might as well not click-and-place but click-drag-a-box instead, when placing a new image. After placing, you can always check the dpi in the Info panel and/or the scaling in the Control panel.

What happens when you drop an .AI file onto the Distiller?

That font is Scala Sans, but I cannot see whether it’s the normal variant or the Pro — “Pro” has Lining Figures.

Zajormita, can you check if you see Lining Figures in the Glyphs panel for this font? If you do and you hover the mouse over one, does it say something like “lnum” in the pop-up?
Another way is to check the regular numbers in the Glyphs panel. If they have alternate forms, they have a small triangle in the lower right of the square the number is in. Click the triangle and gold down the mouse to see what those alternates are.

“Without utilizing third-party scripts” — why? Do you prefer having to write such scripts yourself?

Anyway: InDesign does not have a 'preference' or a 'preset' for the vertical position of diacritics. All that Peter's (free!) script does for your n-tilde and e-acute is retrieving the correct single character from your font, and the way it looks on your screen is the way the font is designed. It's a single glyph, and you cannot somehow “move up” a part of it with InDesign — not without converting the character to outlines, at least. The vertical position is, in this case, determined by the font designer.

An alternative is to use separate “n” and tilde character, and “e” and acute character. In most fonts, the tilde and acute are available as single codes; then, all you have to do is kern them to the left (as these are typically “spacing”), and use Baseline Shift to move it as high as your client desires.

(this work-around simply not practical enough).

I'm afraid there is no “practical” way to do this. You might try to convince your client that this is the way the font is designed.

Easy. Use this:

^.+?:

It comes down to this:

^ from the start of a paragraph ..

. match any character ..

+ .. as much as possible ..

? .. and then the shortest match ..

: .. up to a colon.

The '?' is necessary here because without it, the '+' would match as much as possible, all the way up to the very last colon in a single paragraph.

Try this Javascript (on a copy!). First make sure your measurement units are in points! Or else it will try to work in centimeters or inches, or what-have-you-got, and it may even do something — but not what you wanted it to.

It first gathers all 'pageItems' that are 'inside stories', which is what an anchored object actually is. Then it calls a small helper function that determines if the height (as given by geometricBounds) is in the neighborhood of your 25.337 pts. It needs a bit of a fuzzy comparison, because InDesign doesn't really show all fourteen decimals it internally uses — your anchored object may in fact be 25.336999999 pts high, and comparing it against exactly 25.337 would return “false”!

Then, if a match is found, it uses the 'add to' subfunction of the 'resize' method to add 4.903 pts.