Hi Bill,
1) The IP address of the VC server is stored in each server here: /etc/vmware/vpxa.conf . You can't use a DNS name at this point, but you could change the IP address there after the VC server is replaced and you should then be OK.
2) Your ESX hosts willl be OK for 14 days if the connection to the license server goes down so your VMs would not be affected in this situation.
Are you going to be running SQL 2K5 on the new VC server or a seperate server? In either case, I would suggest moving the database first and then the VC install as a seperate change.