Можно временно установить переменную перед выполнением в Bash. Это будет доступно команде сразу после.
JAVA_HOME=/path/to/java sudo /sbin/service tomcat start
If the NAS supports NFS or iSCSI then you can certainly use it as a datastore for vSphere.
Depending on which it supports and which you want to use, the setup is slightly different. Which does it support and which do you want to use?