Do you really mean a bridge (which connect two different networks)?
If I understand correctly you have a non-wireless router downstairs and want access upstairs with the addition of NAS and a print server.
If so you could get an Apple Airport Extreme (AE). You could create a wired connection from the AE to the router - this would then give you wifi all over the place. The AE also has two USB ports in the back so you can plug in a USB printer and it will then become a network printer; you can also plug a USB HD (or more if you use a simple USB hub) in and that then becomes a NAS device.
If your network coverage isn't good enough (i.e. long thin house) then you can add one or more 'normal Airport Expresses and they will seamlessly extend the existing wireless network.
Very simple and just works.