I've heard that you need to rewrite the story of a movie if you want to adapt it into a comic, because the medium and format is completely different. However, I am not sure what are the considerations that need to be taken into account to adapt from one media to another. For one thing, a comic is much shorter, but is there all there is to it? Does simply writing a simpler and shorter story is the only thing you need to do or is there more to it?
Actually, comics and film or television lend themselves really well to cross-adaptation as the 20 plus years of successful Superhero films no doubt show. The two benefit from the fact that for that most films (and some television shows) are first go through a storyboarding process to visually describe the scene to the people who have to visually render it. Though not every work will get this treatment, for heavy special effects films and animation, it's an almost crucial first step as the director needs to be able to visually show the actors, stunt men, cameramen, animators, and the critical "Best Boy" (I don't know what that job entails, but I always notice it in the credits and it's a pretty high billed credit to boot) all what they have to do to achieve the scene.
These storyboards allow for the easy translation of the film to comics as storyboards tend to have the same quality as comics... they're a bunch of pictures with the character's movements detailed so that the cast and crew can properly block on set (Blocking being the stage term for posing and positioning of actors and set pieces). Depending on when in pre-production a cast is solidified, the storyboards might take on a characters nature of the actors hired to play the role but if not, the character will often look very close (especially true in animation where the actor's work is done with a lot of lead time to the animation. Many big budget animation studios will make characters look like the actors (Disney has a history of this) and many lead character animators will watch the voice actor deliver the lines and tend to draw based on this input... a voice actor with live acting experience will tend to emote in the sound booth and be very physically animated while recording).
As discussed, many Superhero films work because they are predominately comic book in nature. The film adaptation of Alan Moore's Graphic Novel "Watchmen" was almost beat for beat rendered into live action for the film adaptation (The ending being the most glaring part that wasn't, given that it was drastically changed). Several other famous superhero films will attempt to render famous comic panels in scenes (there are numerous live action and animated takes on Superman that try to mimic the cover of Action Comics #1 and Spider-man: Homecoming did a fairly accurate adaptation of "Amazing Spider-Man no. 33" having Tom Holland's Spider-man lift a staggering amount of debris. In both cases, the panel or panels had little connection to the film's plot or source plot. Superman lifting the classic green car overhead, engine oriented towards the ground, is normally the culmination of a scene set up to homage the cover. In Spider-Man: Homecoming, the plot has little in common with Amazing Spider-Man. In fact, the villain in the original story is Doctor Octopus, not Vulture, though the emotional and physical weight of the scene is captured (in case you're wondering why the storyline wasn't adapted, that's because it already had been... Spider-man 2 was largely an adaptation of the arc that Amazing Spider-man no. 33 culminates... it's iconic Subway Train fight sequence serving the same purpose as the lifting weight scene.).
Other films borrow from Comics a lot more. "Spider-man: Into the Spider-Verse" takes a lot of visual cues from the comics, with a lot of scenes and transitions looking like they animated a comic book page. Miles' "loud thoughts" are rendered in yellow boxes, a popular device for showing character's internal thoughts in a comic book (previously, it was the narrator's box, though a non-personified narrator in comics is rare in the modern era... and even then, it's normally revealed to be Uatu the Watcher if Marvel or a similar power if DC). They even refer to the web-shooter's iconic onomatopoetic sound of "Thwip". Not only does Peter B. Parker breakdown web-swinging as "Thwip-Swing" when training Miles, but little "thwips" also appear when webs are shot during the sequence.
Watchman, as mentioned before, looks like a movie version of it's comic and certain parts (namely the "Times They Are A'Changin'" introduction sequence, which visually provides a lot of the supplemental material that was portrayed differently in the Graphic Novel and is done in mostly slow motion live action which looks like a motion comic (a voice acted retelling of a comic, using the original art with some slight movement but not fully animated)).
And of course there's Ang Lee's Hulk, which used a lot of unusual scene transitions to create a comic panel like effect. Having actually seen the comic adaptation, it helps lay out the scenes. However' it's still Ang Lee's Hulk.
As for how to break up the issue, most comic stories are not contained to one issue but rather an arch that would last for 2-6 issues dealing with one storyline and will be collected into a single trade paperback that will be released at the arch's conclusion, although there are no hard and fast rules (2 issue stories tend to be "filler" or comic relief fluff used to pad out a trade paperback when it's main storyline falls short). Some miniseries, like DC's 52 run for much longer (52, having, well, 52 issues... specifically, the series was doing a comic book version of "24" where the entire storyline followed a year in "Real Time" as a new issue was released once a week for 52 weeks.
For a film, one could probably structure the release in either a 3 issue series, each issue following one act of the film (assuming a 3 act structure), or a six issue series following 1/2 of an act each.