1. Correct, with some reservations. It depends on how you save data. Usually yes, because Aurelius will know which columns were changed. But depending on how you use Aurelius, it will log that all fields were modified, not FirstName, only. If for example you call Manager.Update(Entity) and Entity was loaded from another manager, Aurelius won't know which columns were changed - it will perform an UPDATE statement in all columns, and will log modifications to Echo telling so. But usually, yes, only modified fields in each client will be replicated.
2. The most "recent" one, yes. And the most recent one is not even necessarily the one that was last modified by the user. It's the one that is last imported. You might have user A and B modifying the same record, in that order, but it might happen that replication data from user B arrives first in the server than data from user A. In this case, A will win.
There is no mechanism to reconcile this, because everything is "asynchronous" and decentralized. And even consider this scenario: what if record in being updated from user B, but the same record was updated from user B nine years ago. Should a dialog box be displayed for the user?
But I digress, in summary it will simply apply the last modifications.
3. Again, last wins. It might be first deleted and then reinserted upon update. Or it can be updated, and then deleted.
Note that you can add Aurelius version control, which is an Aurelius-specific feature, and that will be applied to Echo replication as well:
http://www.tmssoftware.biz/business/aurelius/doc/web/concurrency_control.html - http://www.tmssoftware.biz/business/aurelius/doc/web/concurrency_control.html