The Apexi AFC NEO is just the newest version of a piggy back fuel controller, it pretty much tricks the ECU aloowing you to adjust some fuel parameter. For the money you could get a RTek ECU upgraded stock that will allow for adjustments or you could even pick up a Megasquirt stand alone for even more adjustability & cover timing as well.
Look here I have a short run down on different piggybacks & stand alones. The links provided will give you the info & pricing on each.
http://www.rx7forums.com/forum/showthread.php?t=2194
A wideband is used for tunning, it will tell you what the Air to fuel ratio is. There are quite a few different widebands out there. A few of the common ones are the following.
Innovative -
http://www.innovatemotorsports.com
PLX -
http://www.plxdevices.com
Zeitronix -
http://www.zeitronix.com
NGK -
http://www.ngksparkplugs.com/product...rmance/afx.asp
AEM -
http://www.aemelectronics.com/wideband.../digital-wideband-air-fuel-gauge-25
Dynojet -
http://www.dynojetwb2.com/
Fast -
http://www.fuelairspark.com/Products/details/meter/default.asp
Autometer -
http://www.autometer.com/wideband