Database Native web services - load balancing, Instrumentation , security

Hello –
I’m proposing use of Database Native web service in our company. Our architects are asking following questions so appreciate your help

a. How do you load balance across the DB WS (is there a way to use the F5 to detect downtime and balance the load across the DB servers)? We will be using RAC configuration with 3 nodes.
b. Our architect have security concern as user id/password information are in the web service URL, which may prove to be an issue. Is there a way to mitigate this risk?
c. Instrumentation in this approach (db native services) is questionable due to development/auto gen of the service logic from the DB itself. We may investigate wrapping the services with OSB to give us an additional instrumentation, policy enforcement, endpoint mediation and security proxy. Thoughts??