I have no experience in data backup

, hoping a backup guru can shed some light.
1. I know it can vary, but roughly how long it would take to backup 50 GB of data, let's say Veritas is the SW and tape dirve is an HP one? Assume tape drive and data are all in a data center (not through WAN, T1 or frame network)
2. Is it common to backup an entire server daily? If so, how do you restore a server, e.g. server blue screens and can't load to OS? Do you just copy the backed up data to the server?
3. Do you backup data/server based on IP, hostname or something you can specify?