Automount network drive on startup osx. This will show you how to automount a network drive when you login to osx lion. This method will persist through a reboot, so your drive will always be available.
The advantage of doing it this way is that every time you log in the drive will be mounted. You wont need to manually do it from the finder > Go menu. You wont have to enter you login credentials every time you need a file from your NAS drive.
Once you have your network drive mounted in your mac, you can get its content indexed by spotlight. Follow the instructions on this page: how to enable spotlight on a network drive
Sources: apple support page on login items