What the core actually is
Every Ether Vessel install starts with the same small, stable core: authentication, roles and permissions, a module registry, a theme registry, platform settings, an audit log, and a disaster-recovery backup system. The core doesn't do much on its own -- real capability comes from modules like CMS, Wiki, LMS, and Metrics, all described on the Modules page.
Cloud or air-gapped -- the same platform either way
Nothing in the platform requires internet access to function. Licensing is a signed local file, not a phone-home check. The default mail driver just logs instead of sending. Backups can push to a cloud destination (S3, R2, and compatible providers) if you want them off-box, or stay entirely local if you don't. The same install process works whether you're running in the cloud or on a server with no internet access at all.
How a module actually gets "installed"
This is worth being precise about: every module ships inside the platform release itself. There is no separate module download or install step today. What you're licensing is access to a capability that already exists in your install -- licensing and enabling unlock it, they don't deliver new code.
To turn a module on, go to Admin → Modules and enable it. Behind the scenes, the platform takes a full backup first, then runs that module's database migrations, and only then marks it enabled. If anything fails partway through, the module is left disabled and you're given the backup id to restore from -- nothing is ever left half-on.
How disabling a module works
Turning a module off immediately removes its public pages and functionality. It does not touch its data. Everything you created while the module was on stays exactly where it was, and stays exportable from that module's admin screen even while it's disabled. Re-enabling later picks up right where you left off.
Updates
Updates ship as whole-platform releases, not per-module patches -- because every module's code already lives in the same release. There's no notion yet of updating just one module independently of the others.