I don't know if a vendor will rip files to a hard drive and send it to you as they usually put everything on DVDs. Given your volume, it's not a bad idea to have them put it straight to the HD, but I'd still ask for the DVDs as backup. If you just get the DVDs, you then know exactly the amount of storage space you need for your files. No sense in buying 2 terabytes when one will do.
As for drive type, so long as it's formatted in a way that both can see you shouldn't have a problem (I think FAT32 will work). Most complete NAS solutions you buy will help walk you through issues like that. I recommend going into Best Buy, walking over to the Sonos display, and telling the techie exactly what you want to do. There are tons of NAS options, but if music is the only purpose you are using it for I would opt for the less expensive models. I'd steer towards one that spins down the disks when it isn't in use (or has a manual off switch) - your drives will last a lot longer. Avoid the expense of RAID by backing up your NAS with a simple USB drive or two.
To use iTunes, you will need a computer running. Sonos does not require a computer to be on (the zone players act as the device that decodes and plays files).
As for drive type, so long as it's formatted in a way that both can see you shouldn't have a problem (I think FAT32 will work). Most complete NAS solutions you buy will help walk you through issues like that. I recommend going into Best Buy, walking over to the Sonos display, and telling the techie exactly what you want to do. There are tons of NAS options, but if music is the only purpose you are using it for I would opt for the less expensive models. I'd steer towards one that spins down the disks when it isn't in use (or has a manual off switch) - your drives will last a lot longer. Avoid the expense of RAID by backing up your NAS with a simple USB drive or two.
To use iTunes, you will need a computer running. Sonos does not require a computer to be on (the zone players act as the device that decodes and plays files).