I have a similar setup (F450, Naza M, GPS, Dx6i, AR7010). I use a camera gimbal, so with only six channels I can't get IOC, so I can't advise you on setting that up.
I can however give you the setting I use to get all 4 flights modes. I use GEAR and MIX like this:
GEAR 0 + MIX 0 = manual
GEAR 1+...