1) No, you don't have to "may as well use the rest of the parsnips" in this soup. I love parsnips, but there was a reason why the recipe only called for two of them. The borscht is good, but the parsnips are a little too pronounced, and make the soup a bit too sweet overall. I could probably improve it a bit by adding more salt, or by adding some seasoned salt, but I don't think I need to be adding needless sodium to my diet.
2) Don't burn it! It was my fault for adding frozen chicken broth to the soup rather than thawing it first. By the time the broth had thawed, some of the veggies had burnt pretty badly to the bottom of the pot. I managed to remove most of the burnt material, and it doesn't seem to have had a negative affect on the flavour (well, not that you can tell through all of the parsnips) but it's an aesthetic thing. I don't like having little black bits floating around in my soup.