will all NAS boxes serve files to a Linux box without any special drivers/software being needed?
Yes. Most boxes are running Linux anyway.
I would have recommended Buffalo until my unit had a fit (see elsewhere). Upside: you can supposedly hotswap a failed drive. Downside: actually you probably can't.
In the office, we have cheap Synology boxes: two RAID 5, one JBOD. The RAID 5's back up the network, then they back up to the larger JBOD. It's software-based RAID so not particularly fast. You can buy them in a range of capacities. In some markets they are also sold without drives. Some versions include media servers, and autonomous bittorrent clients. Downside: need disassembly to replace a failed drive.
Two miserable incidents with the Buffalo have changed me from "software RAID5 is good enough on my home network" to "Hardware RAID 1 or maybe RAID 10 is where it's at", but in reality I guess most consumer RAID boxes will fit your needs.