Made the call, I am going.
I am asked to shoot the wedding from different perspective, kinda shooting from side line. It will be like a documentary style, no interaction, no posing. Most likely I will be a 3rd photographer, others will do traditional/candid I assume. I was thinking of shooting with just one lens preferably a prime (85 f/1.8 or 100 f/2.8), now I am not sure. My guess is I would be at least 15-20' away from the bride/groom, would I be able to tell a story with one of these lens or should I go for 50 f/1.4 (Point to note, I won't be close). I am not interested in zoom lens, but if that's the one which is suitable for this work, I will go with that option. In that case, probably I would end up with kit lens. Not sure about the body, can be an APS C or FF.
I started doing some research, I am not sure if I will be needing an external flash considering the distance I will be working from.