The original was some metric size, 5mm I think. Yes, 1/4" auto hose will fit but the O.D. is bigger so you won't get those protection springs back on there. Same for the engine breather hose, there's an auto one that fits the nipples but not the protection springs. I use the hose from Mike's and highly recommend it. It's a dead ringer for the originals. It is thin wall so those protection springs can be used as well.
For the carb vents, just some clear plastic hose from the hardware store should do, or maybe if you have an extra battery vent hose that came with a new battery and never got used.