The OpenGeo Suite sounds like your best all in one solution
Though understanding the steps will help your build the web mapping application you want, here are some useful links that show you what can be achieved.
"OpenLayers provides vector editing capabilities previously only available on desktop clients completely in the browser, including snapping, splitting, and basic shared boundary editing backed by GeoServer and the WFS-T standard. With the OpenGeo Suite, make edits from the browser directly to an enterprise database all directly on top of Google Maps tiles."
There is a New Openlayer Editing toolbar available here.
Geoserver works best with the a transactional Web Feature Service (WFS-T) allows creation, deletion, and updating of features. It can be setup with the additional Oracle Drivers to take data to and from oracle.
Openlayers WFS-T example - http://openlayers.org/dev/examples/wfs-protocol-transactions.html