Changing FireFox Sync URL ?

Yes, I guess so. Do you want to use your own sync server?

Yes, I guess so. Do you want to use your own sync server?

Yes.

Sure: mozilla-services.github.io/syncstorage-rs/#connecting-to-firefox

Must is still connect to a Mozilla account ?

It doesn't have to, but is the easier. If you want also self host the FxA stack, you can, and can use that then.

It doesn't have to, but is the easier. If you want also self host the FxA stack, you can, and can use that then.

How can I set this up; is it all in the same link you posted above ?

It starts at mozilla.github.io/ecosystem-platform and the setup is described at mozilla.github.io/ecosystem-platform/tutorials/development-setup for just dev use — no idea how feasible is to run own production version (it's massive) — most of the popular sync self–hosting articles just use the hosted version for probably this reason.

(Sync only stores the encrypted data. Account is the part which handles the cryptography to extend the keys for the end–to–end encryption of the synced data.)