This is mostly general CSM advice based on what you are taking. If you have a better idea of how you like to play I'll give you ideas in that direction.
All in all, I find the MoN to be generally useless and WAY too expensive. I would prefer the MoK on a 10 man squad. You'll lose furious charge and fearless, but you'll basically have a berzerker unit with better weapon choices.
Personally, I like the plasmas in the berzerker squad. I feel like it rounds out the ability of the squad with a S7 weapon with very little risk. If you wanna rock 10 of em I say go for it. Your increment of killyness on the charge against a vanilla 10 man SM squad goes from 47% to 59% with the addition of 2 guys. At I5, that just means 1-2 fewer guys get to swing back.
For the vehicles... DP on the LR is key. I like the Reaper on the Defiler. The lascannon on that dude is a waste. Rhinos are the VW busses of 40k. Keep em basic. I wouldn't put leather seats and Bose surround in a VW bus, so don't waste expensive upgrades on the Rhino. Extra armor and/or a combi weapon is about it.
Remember what I said about the MoN? Forget it when you do your demon prince. Since he is immune to instant death, the extra toughness actually helps. WS <4 opponents will need 5+ just to hit. And the T6 will make it so only guys with S8 can wound on a 2. Warptime, yes. Not bad for 175 pts.
I still haven't found an effective way to use my chosen. I like everything about them though.
Consider a 3 man squad of Terminators with a combi-melta x2 and a combi-flamer. Maybe a chainfist. Deepstrike them in to scare the crap out of vehicles and divert fire from your main force. Again, for 120 pts your can't go wrong.