You will need to get a complete setup with a controller and most setups will have an output for use with a datalogger.
The gauge is a nice thing to have so you can keep an eyeball check on the AFRs.
The simplest and cheapest setup is the AEM wideband, IIRC they are around 200 bucks now and have 2 output wires. Once of which you can splice into your EGR signal wire and setup Binary editor so that you can datalog AFR using the EGR output wire.
Ive been using an AEM for a few years and have great success with it.
If you have more questions on it send me a PM and i can give you some more info or something on setting it up.
If you plan on keeping a Closed loop in your tune you will keep at least one narrowband. A WB is completely a stand along thing on a stock EEC based car, with a standalone EFI you can use WBs as part of the feedback. But with an EEC it wont actually have anything to do with the tune, you just tune the car to make sure the AFRs correct where your actual AFRs are matching your fuel trims.