Between the SNDB, the paper money Wiki, and the Charlton catalogue, plus whatever the CPMS publishes these days, there are enough resources for any collector to get their questions answered. All you need to do is take the time to access these resources and read them.
Also I was wondering if there was a place I could find a list of the rare harder to find serial number prefix-signature combinations.
Ahh, yes, the old magic list question. Who needs resources when someone has done all the work extracting the most pertinent information, putting it in list form, and is willing to give it to anyone who asks (for free)? It sounds like you are looking for the stripped-down online version of the catalogue. If it exists, I don't know anything about it.