Even though I recently built a Naught, for me they just don't have the umph to make them really worthwhile for the points. Of course I haven't glanced at the formation your planning to use, so take my advice with a grain of salt.
Between the two, I think the Mork is the better choice. With the KFF, which of course you'd put on, its the more expensive of the two, but giving the guys around it the Invul will really help, not to mention help turn the Mork into more of a bullet sponge, which trust me you want (anything to pull shots off of boyz mobs is a necessity with the new Mob Rule).
More than survivability though, I think the KMB is a better choice than the Flamer, and barring a real dreadful scatter I think you'll usually hit just as many if not more enemy models with the KMK than the Deffstorm. Of course that's not mathhammered, it's just my opinion, the 3D6 shots is appetizing, but unless you have mad D6 luck I don't see it rolling more than 9 or 10 on average and that's before rolling To Hit. Now if you could mount a Gitfinda on a Gork maybe I'd be more inclined to give it a shot, but even then I still think you're more likely to do better damage with the blast.
The one game I've seen so far using a Nought was of the Gork variety, but it didn't last very long. Even with the 5 HP the noughts just aren't as survivable as you'd imagine just with the relative standard array of heavy weapons. If your local meta isn't filled with Lascannons, B/D Lances, or Gauss I think you'll have a better chance with a Nought than most, especially if your taking a gaggle of other walkers which I'd imagine is the Dreadbash slate.
As for the electronics I unfortunately have nothing, but I'd recommend finding a hobby train store in your area, a lot of model train hobby-ests use blinking LEDs, so there's a chance that such a shop might have something on hand that you could use. There's even an outside chance they could help with a how-to, but you'd have to get really lucky with that.