Depending on the area you might have a better shop that will show you how to build it, or at the very least youtube will have builds you can watch and learn from or even a local might have half a clue and get you a good build.
Shops like that need to called on the carpet for the bullshit artists that they are.
Ok the low res or no res or 9.99 ohms is a couple of things. Your 510 pin might be pushed down to far was a common issue with vamos, a simple o ring repair might be in order.
You might have a short in the atty or it is simply built to low for the vamo to fire it.
As for wire a good starting point is 28-32 ga. it is cheap and Temco is fast shipping on a-1 kanthal.
As for build I disliked my gennies with a mad passion but others love em.