With a cheap, plug-in doorbell (remote on door, chime plugged into outlet, no wires) would a lamplinc or something similar sense the state change and be able to relay that info to my 994? I have a normal doorbell in front and the cheap doorbell at the back door. Currently you can't hear the front from the back of the house or the back from the bedrooms. I want to do something (light blink, text message, etc.) so I don't miss either. The front is a 2gig doorbell that will be put into the system when I get my zwave adapter.

I don't think there's  an Insteon module that will work with your setup. The chime most likely doesn't draw enough current to trigger a Insteon Synchrolinc 2423A5, but you may want to look into it.