Dynamic Account Segments

Hi All, this is one for the accountants as it will send everybody else to sleep! I've discovered that you need to run conversion routine 11073 when copying companies, otherwise only a few Business Entities (table BusEntity)are created rather than the 300 or so system ones that exist. Having done this and created a dynamic segment using the (system) sales territory entity, I have three questions:

1) Why does it say "updated manually" against the dynamic account in cofa maint?
2) Do I need to change any posting rules as a result of adding a (system) dynamic segment?
3) Does it matter whether I use the standard of extended posting rules to get the dynamic segment working?

All comments gratefully received.