Ah that’s fine then… 90s and up should be fine I think 
Now, here’s my take on it:
I went in via the reading route, thinking it wouldn’t take long until I’d be able to follow JP subs. Well… I was wrong: it’s one thing to read a book at whatever pace you’re comfortable with, it’s a whole different matter to be able to read those subtitle lines in the 1-2-3secs they are displayed.
I reckon you or better, said, me - can’t speak for anyone else - I’d need a few hundred books under my belt to get to a suitable reading speed to keep up with the subs.
Unless, of course, one would be willing to pause-resume most of the time but… then you’re no longer watching a film, you’re just reading a script 
If for you it is easy to learn vocab without needing their “visual” form (writing), it might be a good idea to prioritize this and listening skills, to get you to your goal faster?
That’s not to say ignore reading and kanji learning, though - subs will still come in handy when the speech is muffled and whatnot.
As for grammar:
If you’re not intending to take JLPT exams or getting your own speaking level up right away, perhaps just skim through the theory (in textbooks or online resources), rather than spending much time on that and drilling practice and so on. And put in that leftover time into vocab learning and listening practice.
My feeling is N3 grammar will get you most of the way for film dialogue. At least insofar as contemporary-set dramas go.
I’ve recently started N2 grammar points (on Bunpro, no textbook) and the few I’ve seen so far I can’t say I’ve heard in dialogue - although it is entirely possible I missed them 
Bunpro is cool enough and all their grammar points are accessible even without a subscription, albeit without access to SRS.
Another great resource (IMHO) is Satori Reader: their stories come with full audio so can be useful for both reading and listening, plus they have a wealth of extremely useful side notes and explanations on grammar.
Subscription based, but the first few chapters of each story are free.
Oh and by the way:
Natively have community-backed difficulty gradings for films, anime, TV series too - the database isn’t as large as that for books, but it’s better than nothing. At the very least, it can give you a rough idea of what to expect.