So, residency rights... here’s the main points based on my re-read of the draft text.
Everything is reciprocal, EU - UK citizens have same rules for rights in the host nation.
Continuous residency of five years gets you permanent rights.
The period can include post transition period, as well as before.
Continuous can be broken... here’s the specifics, which are part of a previous EU directive on freedom of movement:
“Continuity of residence shall not be affected by temporary absences not exceeding a total of six months a year, or by absences of a longer duration for compulsory military service, or by one absence of a maximum of twelve consecutive months for important reasons such as pregnancy and childbirth, serious illness, study or vocational training, or a posting in another Member State or a third country.”
Also:
If you leave for five consecutive years, you can lose your acquired permanent rights.
There’s more detail about admin processes, e.g. not invoking extra charges for applicants etc, but the above are the key points I’d say.