A print server would simplify your printing to a great extent. Is your router also wireless? I would think so if one of the Macs connects wirelessly. I would hope you don't connect it through one of the other Macs.
If it is a wireless/wired router then your connection only needs to come in through your router from the printer, and a wired connection is best. To that end either the Keyspan server or the D-Link printer server would work well.
