Hi!
I provide on-site EA support for a multi-project, multi-user client, but they don't use Oracle so I don't have anything specific on that.
In general, EA gets unhappy if it loses the DB connection; you typically see this if you disconnect a laptop from the network and then reconnect.
It may or may not be able to reestablish contact, but the safe way is always to shut EA down and restart. If you're using lazy load the startup time is pretty acceptable.
I'm not aware of any in-EA settings that affect this, but you may be able to tweak something in the ODBC connection.
If your setup employs slow connections you might want to check out the WAN Optimizer, which is available as a download from this site.
In order to copy an entire model repository you use Project Transfer under Tools -- Data Management. [In EA parlance, one repository contains one project, which in turn holds a number of packages, elements and diagrams, ie the models, although "model" is a fuzzy term that I try to avoid.]
This allows you to clone EA repositories across database engines, and to/from .EAP files as well.
However, certain settings are per client, not per repository, and these obviously won't be transferred. This applies to most of the settings in the Options dialog, such as the web home page etc. Most of the settings in the Settings menu, on the other hand, are stored in the repository and so will be copied during a project transfer.
Setting up an EA modelling environment can be a subtle art in its way, and you need to take into account things like information security policies, CM policies, desired level of model reuse and of course how the models should be used (for reading only, or document generation, or code / schema generation, etc). But a simple setup shouldn't take more than a few hours even from scratch.
There are some basic admin guides on this site in the
http://www.sparxsystems.com/resources/whitepapers/ section.
Check out "Deployment of Enterprise Architect" and possibly "Version Control in Enterprise Architect".
HTH,
/Uffe