Basically I have an iphone that has non working wifi, and I dont have 3g/edge etc. Are there are products for iphone that could allow it to have a wifi external adapter or possibly a dock for ethernet?
exactly what he said you need either Wifi or 3G/Edge to use internet on any iPhone.I am going to have to say no.
You can use an app, which you can find on Cydia, called iBluever to use your iPhone's Bluetooth in order to get internet IF you have another mobile phone that has internet.
And how would I be able to d/l that app?
If got it, get your answer via Google, there are some guide on how to use it.