Upgrade of Multi node11i to Single Node R12(applications)

 We are performing an upgrade of current 11i Application to R12. 

Below is the Architecture information of current 11i

Server1: DBNode & Admin Node

Server2: Web & forms Services

Planned Architecture of R12

Server1: DBNode

Server2: All Application Services.

My question is about change of concurrent node from DBServer to Webserver. Is it mandatory for us to mount $APPLCSF directory to be mounted across the server(DB & appllication Servers) to prevent any issues while execution of concurrent requests.

Also we have some external interfaces for getting data from external servers and this interface directories are mounted on DBServer(11i) and these directory information is set in utl_file_dir. So, do we need to mount this directories in both DB & application servers of R12 Instance.These directories are used for concurrent request processing.