Multiple Macs in house - SD to NAS???

[MacAfrican]

Hi,

We have a PowerPC MacPro, an iMac and a MacBook Pro in the house. Originally I used SD to make bootable backups to two dedicated partitions on the second HDD in the MacPro, then later added an external Lacie to the iMac so that it could also have two bootable partitions and for safety sake the iMac and the MacPro also hosted sparse image files of each other.

I've now gotten a MacBookPro to add to the family and we are running out of space in the various HDD so I was getting (well sort of already have) a 4TB WD ShareSpace set up in RAID 5.

Original idea was to be able to have a couple of partitions on the NAS so I'd have a partition for each Mac to which SD would make bootable backups. haha..

Q1: Is it entirely impossible for SD to create a backup on a networked attached drive, which backup is then also bootable?

It also now transpires that the WD ShareSpace cannot be partitioned - looong story. Q2: I have not yet checked how it was formatted either but presumably the ShareSpace must be formatted Mac OS Extended for me to have any joy - bootable or otherwise with SD?

Q3: if an external HDD with a suitable partition is connected to one of the Macs, can I use SD to create bootable backup in that partition from another Mac on the network? Q4: would that partition then be bootable from the source Mac as long as the Mac with the external HDD is on?

Am I therefore doomed to:
1. Use the ShareSpace as a big dumb drive - can have SD back up to it but no way to have any part bootable and in any event needs to be Mac OS Extended format
2. If I do above am I safe by backing up into folders on the ShareSpace - I previously backed up into dedicated partitions?
3. Use two external HDD, each with enough partitions, that I then physically connect the external HDD to the Macs every now and then and create bootable backups to their relevant partition?

BTW, OT for SD, but the WD ShareSpace also cannot work with TimeMachine...

Thanks in advance from the bottom end of Africa!