figure of 8 is not a very good idea for capuring multiple participants (not good for any dialogue capture). you are likely going to be holding the boom above camera frame shot, so any ceiling reflections are gonna come back to the other side of the mic. also, if they start speaking at the same time, the one on the rejection side will be completely rejected.
go with NT5 - cardioid is a preferred interior choice, and it will be good for outside too, while for noisy exterior a shot-gun mic or lavs would be better. furtermore, NT5 is by far the easiest of the three for boom manipulation - C414 would be next to impossible to deal with.
I'm a boom operator in a couple of days, and I am to provide the mic as well. Recording interviews for a TV series.
Any suggestions on mic/mic type?
Indoors or outdoors?
The normal mic. in these situations is the Sennheiser MKH 60 or MKH 416 - both short gun mics.
These would normally be in a full Rycote basket windshield kit with ConnBox and Windjammer for outdoor work - for indoor work a Rycote INV-7 would be fine, but you *would* need a foam windshield to minimise wind noise from moving the mic.
A short gun is needed so you can set good sound while keeping the mic. out of shot.