I have 2 distinct locations, A and B, each with their own residential lan, a couple pc's, a notebook, etc....
Site A has a NAS (a DNS-321, I have toyed with the fonz fun-plug to run linux programs, for example I have vsftpd running on it now). Site B just has a couple pc's, a network printer/scanner etc....
I am currently using cobian backup to backup documents from site B to the NAS at site A via ftp (trying to get sftp to work, but having difficulties)
For a couple of reasons I think it might be beneficial to vpn the 2 sites together to a very limited degree, just for samba/network shares traffic. All other traffic should use the local network connection, ie not be vpn'd. I have a router with DD-wrt (with vpn capabilities) at site A, and could put one at site B as well if need be.
Questions:
1. would it be easy/feasible to have just samba/network share traffic bridged, and would doing so mess up either of the lans (for example if site B is vpn'd into the NAS at A, would the other pc's on the lan at A not be able to see it on the local network?)?
2. Would doing so be easier/more flexible with DD-wrt router at both locations? Or just one at the NAS at A and setup each pc at B that is going to backup to the NAS at A to vpn in at backup time? Or have a permanent vpn connection between the 2?
3. I have no clue about subnets, but reading it appears setting those up to work could potentially be difficult, especially for someone like myself

4. In the end would it matter if my vpn server is at A or B, or could it be switched either way and accomplish the sharing of the NAS at A with the lan at B?
So many options, my head is really spinning....