To answer your questions:

1) 19X11 APC currently (still running in, will eventually switch to a 20X10.5)
2) 20% oil
3) 30% nitro
4) I'm running it on glow at present. Spark plug life on the 170CDi was pretty good but you did have to adjust the spark plug gap every so often.

I flew electric most of last season but I've not flown electric since September, I've gone back to YS. My 170's and 175 have been great so far and I'm not about to give them up just yet. During the winter if you get a break in the weather you need to hit the field quick so having to wait around to charge batteries isn't attractive to me at the moment, I'll just bring out my petrol/YS planes

With electric you do get instant torque but YS aint too far behind. But do your really need instant power? I put a throttle slow on all my F3A planes so for me personally I don't think it is a bit deal at all which reacts to the throttle stick the quickest. My contra does have a lot more pull that my YS but the YS would still ease through P-11 and F-11 so I don't agree with Arch' comment about the vertical snap with YS. The YS also had the same level of performance at the end of the schedule as it did at the start. Electric, whilst improving all the time, isn't there just yet from my personal experience. You need to manage your batteries. Obviously the lack of vibration is a big advantage with electric. At the end of the day you pick the system that best suits you.