Hiya John
Welcome to this crazy forum, there's certainly plenty of advice here, both good and not so....your challenge is to sort out which is which
On the owners manual, there's not really any such thing produced that I'm aware of for the kits available here. Depending on the manufacturer the "build manual" may contain comprehensive instructions or just very basic construction info and sketches. I've built 2 ICV's and the manuals are chalk and cheese.
Not sure where the manual will help with your decision either. The best place to get a handle on a build is on the forum build pages here. You'll see some guys are fanatical with every detail and others just want to get the bluddy thing on the road
As for getting one, you may be able to purchase one from one of the manufacturers, but really, do some homework on which company you want to go with, maybe they'll supply you one then deduct the cost off your deposit on the kit.
Anyway, good luck with your dream. It's great fun.