Idly, how did you end up handling the randoms (especially the backtracks that may or may not happen)?
I took your number of 33% chance, and then assumed 3 actions on enemies at party level. I ignored all backtracking potential.
Now to take a brief break from things people actually care about (FFT) to...things people don't!
I'm going to attempt to calculate Twilight characters in D&D stats.
So...what do we know about Twilight characters?
Edward across multiple instances is reported at moving about 1000 mph (through difficult terrain like forests). Various examples--running from Denali Alaska to Forks Washington in under an hour (800 miles). Running from Port Angeles to Forks through a forest in "minutes" (56 miles), and notably faster than they were driving (well over 100 mph). Making a 5 mile trip through a forest while carrying a human on his back in "seconds".
And some stuff that is easier to quantify in D&D terms. Able to move completely silently to human eyes. Able to move so fast as to basically appear out of thin air to human eyes.
Strength feats are less clear, because nothing short of fighting other vampires tests his limits. Certainly a minivan is no problem (roughly 2000 kg). Nor is lifting a 1m boulder and throwing it a long distance (also roughly 2000 kg). Or snapping off a tree branch that is two feet thick, and swinging it to knock down the original tree (probably 600 kg on the tree branch).
Hmm...well, let's start with the easier one.
Bella Swan:
Strength: 8 (She's very uncoordinated, and not athletic, but takes books all over the place without noticeable encumbrance so she's not ridiculously weak).
Dexterity: 6 ("Significant Klutz" yeah, pretty much).
Constitution: 8 (Well, she's not "unusually prone to disease and infection" that a 6-7 score would imply, but certainly "incapable of a full day's hard labour" for 8-9)
Intelligence: 16 (Yeah, Bella is unusually smart; she figures out the vampirism, picking up on clues that other humans missed. She was in advanced placement classes. She nerds out with Jane Austen for fun. She tricks a vampire who can predict the future.)
Wisdom: 7 ("Seems to have almost no common sense"...or sense of self preservation. This extends to more than just vampires and werewolves, and includes walking down dark alleys).
Charisma: 13 (She's a nobody in Phoenix AZ, but her charisma stands out in Forks enough for her to be moderately popular to the point of making several girls jealous...sooo better than an average human).
Alignment--Chaotic Good? Definitely good (her defining character trait is "martyr") and likes to prove old rules and traditions wrong, so more on the chaotic side.
(Total pointbuy cost: 1 LOLOLOL. Actually I'm surprised it's above 0.)
So...moving on to vampires...there's a slight problem that there's no movement bonus for ability scores. All creatures with 30 base movement speed can move 6 miles in an hour when hustling. This is a lot less than 1000 miles per hour.
Well...ok. There is one way to gain movement in pathfinder, and that's to be a monk. Normal 30 ft pathfinder characters can move 120 feet when running at full speed in a 6 round turn. That's 20 ft/second, 6 m/s. 21 km/h. 13 mph. So...would need to go from 30 ft pathfinder character to like...3000 ft. Roughly a level 900 Monk then? >_>
OK, strength--it seems fairly clear that 2000 kg qualifies as a light load. Strength load numbers are exponential, so...strength score of 45? Something around that.
Alright, so...dexterity. What's the DC check for "with no training, jump out of a third story window, and land gracefully on the toes of your feet so that you don't snap your stiletto heels"? Hmm...yeah I don't really have an answer to that.
OK...so there's DC checks on jumps. But the problem is, characters with high base movement get + bonuses to jumps; at 3000 ft move speed, the bonus to jump would be like...+1200 skill bonus. This allows a long jump of 1200 feet, or a high jump of 300 feet. Yeah, these are pretty similar to numbers in the books. Well...let's pretend that pathfinder did have a way to translate high dexterity into movement, and that it matched this jump conversion. This means roughly 2400 dex. >_>. Yeah, sure, whatever; I really can't think of a time any of them failed anything that could be considered a dex check. Ever.
Constitution. Let's see...the description of 35 is..."Nearly immune to any level of fatigue, illness, disease, or infection- such a creature's stamina is practically god-level" hmm...well they literally don't sleep, don't get fatigued, and are immune to disease and infection.
Although on the other hand "Most undead creatures do not have a Constitution score" -- yeah, this might be more accurate. Probably this.
intelligence -- definitely superhuman. The brain has to process at a higher framerate just to make the sheer speed possible--which creates an appearance of intelligence (basically able to have a minute's worth of inner monologue in less than a second). But reports also include being able to juggle more ideas simultaneously. The long lives also tend to make the vampires have more raw knowledge than most humans. That said...still within reach intellectually; humans outsmarting vampires is rare, but happens. Something like 22 int?
Wisdom -- Well...discounting abilities (Alice, Jasper, Edward) and discounting the kind of skill checks wisdom is based off of (perception...; vampires get huge bonuses to that due to their eyes, but that's a physical trait, not wisdom)...no, vampires aren't especially wise. To the point that when Edward can't read a mind, he doesn't know if a faster heart rate means a positive or negative emotion. I think this is a 10.
Charisma -- ooh, vampires are pretty good at this. To the point of "basically getting free suggestion spells". Not flawless, people can turn on them, it's possible to resist them, but certainly "Renowned for wit, personality, and/or looks" -- which is the 24-25 description. Most people also have an instinctive fear of them, but causing fear is also charisma based. Let's err a bit high--unlike intelligence, where sure, vampires think faster than humans, but there's still big dumb vampires that prefer smashing things to intellectual pursuits, so it's conceivable that a smart human might be smarter than a dumb vampire...but with Charisma this doesn't happen (see: Rosalie as a human). So like...30? Still low enough that humans can sometimes resist persuasion.
So something like...
Strength: 45 (or more? Unclear what the limits are)
Dexterity: 2400 (Admitedly, this is Edward/Neonate numbers. Other vampires will be lower, but still in the four digit range).
Constitution: - (undead)
Intelligence: 22Wisdom: 10Charisma: 30