You could go 25n/25f if you feel your happier with that, you won't have to concern yourself about retards too much either, perhaps 2 deg is enough, more if you go cleaner. I had 1 main arming switch, then 1 switch for the seperate fuel pump for NO2 petrol, and then a micro on carb for WOT off the line. A steering wheel button is perhaps your best way as I doubt you'll be hitting it off the bat anywhere, even once you get used to it all being a stick car. Having a fuel pressure guage thats visible in front of you isn't a bad idea, I had 2 on the cowl.