The recipe you provided does use pectin, but at the end she says she usually strains it (then blends it) to make thicker yogurt.
Most raw milk yogurt I've experienced is either too thin, or lumpy with lots of whey at the top. After I strain mine, I use a stick/immersion blender to smooth it out.
I just looked up the yogurt maker you're buying - I guess it would defeat the purpose if you then dumped the yogurt out to strain it. I make yogurt in 6-8 qt batches so it's more practical to drain it.
Any yogurt with LIVE cultures will work. Depending on the actual bacteria strains in the yogurt you are using, you will end up with different results. I've also found that using one really sweet creamy brand of yogurt doesn't necessarily produce the same result in raw homemade yogurt.
Ask the farm how they make their yogurt - I'm curious how they do it. I would definitely try that yogurt as your first starter. If it doesn't turn out, use it for smoothies or baking and try again. Some amount of trial and error is necessary.
I've tried all the NE Cheesemaking yogurt cultures. With my first cow's milk, the Y4 made the best yogurt. With my other two cows, I found the Y5 to work better. It just depends on the particular milk you're using.
The freeze dried cultures last years. And I split each packet between ~6 qts of yogurt, rather than the 1-2 the packet recommends.
When using fresh yogurt as a culture, use 2-4 tablespoons per quart.