Tuncay -
The volume move command is disruptive, mostly.
There's the time it takes to do the last snapmirror transfer while we quiesce the IO on the front end before updating the VLDB to point to the new volume location.
The default cutover delay is 30 seconds.
See the man page for the command: http://docs.netapp.com/ontap-9/index.jsp?topic=%2Fcom.netapp.doc.dot-cm-cmpr-920%2Fvolume__move__start.html
As for your second question ... NFS 3 will continue to use the same LIF.
Best practice would be to migrate the LIF to the new node when you move the volume.
I hope this response has been helpful to you.
At your service,
Eugene E. Kashpureff, Sr.
Independent NetApp Consultant http://www.linkedin.com/in/eugenekashpureff
Senior NetApp Instructor, Fast Lane US http://www.fastlaneus.com/
(P.S. I appreciate 'kudos' on any helpful posts.)