Question on Lines and Genetic Diversity

Even though I know it will be years (sadly ) before I can possibly own a CsV, I'm constantly doing research to better prepare when the time comes, since how you choose a dog is so vital in the US, with the breed being so new. I am fully aware that in order to keep the breed as healthy as possible, breeders need to maintain genetic diversity. I've seen this a lot more with CsVs than with any other breed, and I think it's wonderful and much more forward thinking than most dog breeders will look.

My question is in regard to reading pedigrees. Mainly, since I'm not a breeder, how does one look at a pedigree and decide there is enough variation between the parents? How far away to you keep the lines? Also, is there a good way to learn about what lines there are? Because for now, all I've been doing is going to breeder websites and looking at which dogs I feel (just from photos) meet the standard the way I would see it (being a total layperson, of course ).

Here's a hypothetical example. Lets say there's a breeder that I love, produces great puppies, and has a solid breeding ethic. However, there is already a dog in the US with a relative to this kennel 3 generations back. While it's only one dog, would it be better to get a puppy from a different kennel, just to add more lines to the US? Or is the quality of the pup justified, even though there will be another dog of similar line in the US?

I hope I'm asking my question well, it makes sense in my head, but doesn't always articulate well! Thanks for your help!