Is WP appropriate for my project, and if so, where do I start?

I have lots of experience in web development but my previous projects were not dependent on a platform or API.
This is the first time I’m trying WordPress as it looks like the best basis to start from.

The website I’m developing is primarily a blog to showcase a collective of streamers.
They post their schedules to the blog, users subscribe and are notified. Scheduled shows are indexed on a calendar.
Some blog posts however are just blog posts.
When a streamer goes live, a video player appears on the homepage.
And so on…

In order to achieve this, users and blog posts require a lot of additional attributes in their respective tables, or some additional tables linking to the built-in wp_ prefixed tables. I’m not sure what would be considered best practice here but I expect the latter.

For instance, I plan to have an additional table in the database containing channel data, which is independent from the users themselves, linking these to 1 or more users with an additional table.
Blog posts need to be identified as events or not, with a scheduled date and a link with the channel.
As well as that I’ll need to implement a few toggles and switches on the dashboard for contributors and the admin, and automated events like sending emails or posting to facebook.

I’m pretty sure no one here will argue against the usage of WordPress for a project like this, but when it comes to customisation I don’t know where to start.
If I were working in pure HTML/JS/PHP from scratch I’d know exactly what to do, but the implementation would take a significantly long time and I’m trying to do this relatively quickly.

I guess I start with a custom theme.
There’s so many php files though to deal with, adding additional fields to a table for instance looks like it’ll be a nightmare to implement.

Any helpful tips or advice?