Using Specialized Categories, and Random Generation

I’m hoping to produce a Website that will serve a number of functions using WordPress, and have some questions about that. It’s a Website for an upstart operation, and will contain listings and homepages for films available under different topics and in different months, some “About” and other relatively static pages, a couple of blogs, and some pages that I hope can randomly generate their content from a given set.

For the primary function of providing the main movie listings and homepages, I’m under the assumption that doing these as blog posts utilizing various categories is the best way to go. The listings page will have thumbnail images with 40-odd-word summaries of the roughly 40 movies available in a given month, sorted by topic (there are currently five topics). For each individual movie, there’ll be a homepage with larger images, write-ups, aggregations of reviews, etc. Movies may appear in multiple months, and virtually all will cycle through a few times over the course of a year.
What I’ve been assuming is the best way to do this is to create categories for numerous months, and check off the months that a given movie is expected to appear, while also creating categories for the movie topic, and with all of them appearing as children to a parent “movies” category.
I figure I’d then create a style for a listings page that calls for the loop, drawing only on excerpts (containing the thumbnail, text, and link to the movie homepage) for the movie posts that in the actual body contain the full movie homepage, with only films in the current month’s category included, and then sorted by the topic category.
I figure that for the movie homepages, I’d create a style for individual posts in the movies category that allows for all the elements I’d like to include in them.
One thing I have to keep in mind is that we’ll only put up the movies as they become available for the first time, but that the homepages will remain even after their first month appearing is over. So, if possible, it’d be best to have the movie homepages reflect in some sense whether they’re currently airing or not, and if not, when they most recently aired and potentially when they’d air again.
Does this seem like the best way to go?
If I go with this approach, my biggest question is how to create it such that the call for movies in a given month will end up requiring the fewest monthly changes. Which is to ask, is there some way to set this up such that I can just change one number somewhere or flip a switch to change the current month from X to X+1, as opposed to going to each call and changing the category ID for the given month (which can lead to much more error)?

My second main question is relating to the front page of the site. My hope is to have two large images randomly drawn from those representing the current month’s movies appear very prominently on the front page, and have them link to those movies’ homepages.
I’ve got very little idea how to do this well. Does anyone have any ideas?

I’d prefer to take a roughly similar approach to the overall movies page, which would draw five images, one for each topic, under headings for each.
Any ideas?