I did a search for O2 wideband sensors but didn't really find anything explanatory on the difference between our stock O2 sensors ( I assume narrowband? ) and wideband O2 sensors, that gets a mention every so often. How does the ECU utilize the readings from them? What is the advantage of wideband over narrowband?

A narrowband will give a general idea of AFR's from 12:1-16:1 however because of the way they work and the resolution they provide, they are only really accurate at an AFR 14.64 (Stoichiometric). Widebands on the other hand are very accurate through a wide range of AFR's (normally 10:1-20:1+). Narrowbands are basically used as a check point for the EEC, and are only refered to during closed loop where the engine is targeting 14.64 anyway, everywhere else the signal is ignored (primarily due to their inaccuracies).

The Ford EEC cannot read wideband O2 sensors, however many, including the techedge wideband I run have a simulated narrowband output signal which it calculated from the wideband sensor. This signal can be fed to the EEC to keep it happy, however the primary reason to fit a wideband is so you can accuratly tune the AFR tables using either an edit or an aftermarket engine management system, and then after that to keep an eye on the fuel system. IMO anyone fitting a turbo or blower should invest in one as it only takes small changes in AFR to blow head gaskets, pistons etc, but otherwise they are a bit of an overkill on a NA engine (except when tuning of course). A wideband is not cheap, it will set you back around $500.