There are several different ways to get it set up, but I’ll just go through the way I’ve done it.
I have everyone set up so they have a home drive on the NAS. I also have several shared document folders, photos, music, pretty much everything I have is stored on the NAS so there isn’t that much I need to back up from the PCs.
I’d strongly recommend putting as many of your files as possible directly on to the NAS for reasons I’ll explain in a minute.
I do still have all my PCs using Cobian backup though, as there will always be some stuff that needs to be backed up. Cobian backup just creates a zip file, so I can easily restore anything I need to directly from the NAS.
In your case, Arq would replace Cobian backup and you would back up (and restore if necessary) directly to(/from) the NAS.
There is a utility that Synology provides for Windows called backup explorer. It allows you to browse offsite backups from your PC and retrieve any file(s) you like. However, this will never be as fast as retrieving a file on your local network, which is why I recommend the backup to NAS option.
Hyper Backup on the Synology is actually pretty good and provides all the functionality (and more) that a home user could need.
It keeps track of your files, compares them to the backed up version, and only updates the backup if the file has changed. It also keeps a number of versions of the backed up files (I think it’s up to 30 versions or something like that).
This means that the initial offsite backup will take ages, but subsequent backups will be very quick. I have about 2.5Tb offsite, and if I recall correctly, it took about 3 days to complete initially. It now usually takes about 10 minutes per night, with some nights taking a bit longer.
I have 5 different backups scheduled each night, for different things (documents, photos, videos, etc)
The reason I recommend keeping as many of your files as you can on the NAS is this: If you do a backup from your PC, you will be combining all your individual files into a single backup file. If any one of those files changes, then the entire backup changes and will need to be re-sent offsite, taking a lot of time and bandwidth.
Another obvious reason for keeping your files on the NAS is that the NAS is usually a lot more fault tolerant than the PC.