I am (was) a big fan of the Atlas signal system. I believe it had the features you list and also the ability to link the signals together to operate from multiple block inputs. I kind of gave up on them since they have not been available for a while now, but I have heard rumblings that Atlas may be remaking, redesigning, remanufacturing them or something along those lines. The big problem for me with the Atlas signal system was cost, not that it wasn't worth it, just that is was a bit above my price range. But, it really is/was a neat system.
Maybe I can find a feature list from the Atlas signals, like from a listing or catalog I might have around here somewhere? It's will probably be cost prohibitive to do all the features that system had, but I guess you never know?
Another idea (probably not a good one) would be to maybe have one PCB with different schematics of designs from 'basic' to 'full featured'? Tthe user could then select how far they wanted to take things and how much they wanted to spend? I'm dreaming here, I think...
Also, I have no ideas about any circuits that would be needed here, but I do realize, to quote GRJ, "Nothing is so easy as the job you imagine someone else doing" which is probably what I am doing here. 
Edit: The post below by The Dude about daisy chaining the signals is one neat feature of the Atlas system.
