cifs datastore for PBS require mount option uid=34,noforceuid,gid=34,noforcegid (= user and group "backup")
and before PBS datastore creation.
You should delete then recreate PBS datastore with correct mount option.
edited: corrected mount options.
Backups to PBS always copy only new/changed data, same data is never stored twice. Dedup can't be disabled.
Hourly backups is ok even if many data, thanks to dirty bitmap (like cbt in vmware).
if VM is shutdown, all VM data need to be read, but only new data will be transfered.
Restore is needed...
sorry but it's bad start if you ask the question about the dhcp.
for information, to start :
Masquerading is like your host become a second router, so it can get its ip from dhcp, then your VMs will need to be another vmbrX bridge + a on an another subnet, they will be not seen by your dhcp server.
but backup is done one after the other.
it's just the backup is done in "background", and imo, Boot need more iops than "snapshot" (if VM is idle...)
my case is backup disk is partitionned, one partition to store vm disk (second backup done inside the VM) and the other partition for pbs...
I guess you use "stop" backup mode, which "shutdown/stop" the VM then start the backup but the VM is started directly not after the end of the backup, datastorage can be "stressed" if you backup of same drive. (I'd the case).
try with "snapshot" mode or even better, try backup once the VM is...