Agent install location and owner

We are a bunch of DBAs and have been installing the agent as oracle under the $ORACLE_ BASE. We are now expanding what we monitor with the OMS to include other databases, WebLogic, and a handful of plug-ins. Usually outside of a database host we don't have the oracle account on those hosts.

What we are trying to figure out before we have a huge mess is:

1) Who should the agent be installed as: oracle, agent, the product being monitored?

2) Should the agent be installed under the $ORACLE_BASE or it's own directory path?

Whatever path we go, we will be installing the agent in it's own mount point.