Anyone able to help clarify the requirements and restrictions around the act of committing, as it relates to card effects that enable/force committing?

In the FAQ, (2.10) Ready/Exhausted vs Committed/Uncommitted indicates that exhausing and committing are to be considered separately, while (3.1) Committing to Stories makes no mention of the associated cost or requirements to commit, but the Core rulebook reads: "The active player decides which of his ready characters in play will commit to which of the three stories, and then commits all of those characters to the three story cards at one time. When a character has been committed to a story, that character’s controller exhausts that character and moves it in front of the specific story card. The active player may commit any number of characters to each story, as long as they are not already exhausted . Each character may only be committed to one story."

Q1a) Is it a requirement to exhaust to commit?
e.g. Julia Brown (Summons of the Deep F17) reads "...Disrupt: If Julia would go insane as a result of a [Terror struggle], sacrifice her instead. Then, search your deck for a card titled “Julia Brown” or “The Sleepwalker,” put it into play committed to the same story, and then shuffle your deck". Must the replacement card exhaust as an additional cost to commit to the same story?

Q1b) Is it a requirement to be able to exhaust to commit?
e.g. Expert Testimony (Seekers of Knowledge F36) reads "Disrupt: When an icon struggle would resolve at a story, choose a [Miskatonic University] character and commit it to that story...." Can only a ready Miskatonic character be chosen, and must it then exhaust as an additional cost to commit to that story?

Q1c) Is there a difference between commit and re-commit?
e.g. Military Bike (The Path to Y'ha-nthlei F102) reads "Disrupt: After a story to which attached character is committed resolves, exhaust Military Bike to immediately re-commit attached character to another unresolved story." Similar to 1b) above, must the attached character be ready to be able to be re-committed with exhausting an additional cost to re-commit to the next story?
I assume the only difference is that re-commit opens a new window to commit, unlike the "commit" ability of Y'Golonac (Core Set F122) and similar cards as discussed in the Frequently Asked Questions section of the FAQ - albeit with Julia Brown (Summons of the Deep F17) from 1a) being 'committed' functioning like a 're-commit'.

Q1d) Does uncommit have any impact on re-committing?
e.g. Noises in the Hills (Dunwich Denizens F68) reads: "...Action: Choose a committed character you control. Uncommit that character and re-commit that character to a different story." Differing from 1c) above, does the explicit text to uncommit change things in any way, or must the attached character still be ready to be able to be re-committed with exhuasting an additional cost to re-commit to a different story?
I assume that uncommitting does NOT cause a character to ready.

Q2) If a card is forced to commit while additional commit-requirement affects are in play, must all requirements be met?
e.g. Binding Worm (The Path to Y'ha-nthlei F114) reads "Characters cannot commit to stories alone." Predator of the Night (Perilous Trials F31) reads: "Response: After Predator of the Night commits to a story, choose a character with lower skill than Predator of the Night. That character must commit to the same story as Predator of the Night, if able." If Predator of the Night's ability is used to select one of an opponent's ready characters while Binding Worm is in play where the opponent has two ready characters, is the opponent then forced to commit both ready characters?

Q1a: No. Exhausting a character is only required when committing it regularly.

Q1b: No. You can target any ready or exhausted character with this effect, even one already committed elsewhere.

Q1c: Not really. I suppose it's only meant to stress that the character must have been committed to a different story before you can trigger the effect.

Q1d: No. Again, I suppose it's just meant to stress that the character does not end up being committed to both stories. It's state (ready/exhausted) does not change.

Q2: Note that Predator of the Night's ability uses the defined term 'if able'. Since the Binding Worm's effect uses the defined tern 'cannot', it will cause the Predator's ability to fail. Your opponent will not have to commit any character.

Thanks for the quick answers, jhaelen.