Help for a Newbie please - Am I doing the right thing?

First - do not confuse the redundancy in a RAID array with backup - it is not. RAID is a convenience in that your array can survive the loss of a single drive (two if in dual redundancy on units with 6 or more bays). No one should ever trust critical or important data to a single device, be it a single HD or a RAID device. If you suffer a drive loss and replace the drive, and during the lengthy and drive intensive resync process you lose a second drive, the array will be at risk.

That being said:

chrismac wrote:
The first question is, does the system back up in real time or only at set times?

If you are talking about the array redundancy, once you save the file, it is redundant. If you are using a two drive array in mirroring for example, the file is present on both drives. If you are talking about about 3 or more drives with distributed redundancy, the parity sectors are spread among the various drives. Thus, if you lose one drive, the array can be rebuilt when a new drive is installed. If you are talking about true backup, where the contents of the array are copied to another device, or the PCs backed up to the NAS, then that is on a set schedule.

chrismac wrote:
In my situation (woking from a laptop connected to the NAS) I presume that whenever I alter a file on my laptop it would be instantly backed up on the NAS? Or are you effectively working off the NAS? (Sorry, not explained very well but I hope you know what I mean).

If you are working on your laptop, then the updated file would only be on your laptop until the scheduled backup time when the contents of the laptop would be backed up to the NAS. The best way is to keep the files on the NAS for once you save it, the array is updated. However, this will not protect the file from errors in saving or accidental erasure. Only a true device to device backup will do that.

chrismac wrote:
Also, if 2 users went to access the same at the same time file the 2nd user wouldnt be able to access it?

If you have a file open and another individual attempted to open the file, they would encounter a file lock. They would be permitted to download a read-only version of the file, but could not save it back onto the NAS without changing the file name.

chrismac wrote:
Presumably I will be able to access the files remotely? I think the main question is regarding the software and how easiy it is for someone like me with limited IT knowledge to set up and use the system?

Remote access can be set up. Some of the features are very straight forward and others will take a little research.