Yes, forgot to mention, if you do keg a root beer you definitely will then have a designated keg and lines for that, essentially permanently. IME, even swapping out seals and such does not remove the root beer taste from the keg, same goes for the lines. Mine is on tap year round so it's not an issue but if you don't plan on doing that you will be swapping everything out for new.
As for the commercial ones out there, I know of Sprechers and Not your Father's Root Beer. Sprechers is meh, don't really know anyone that cares for it. The 10% Not Your Father's is usually what everyone tries to clone and what got me going on mine. There are serious rumors though that this version is not a 100% malt beverage as they claim and there are actually a few articles on this. They also supposedly have a 30% version with the same claim and it's really impossible that it's true. The 6 pack version is 5-6%, bought by Pabst now for distribution and I find it has a really weird aftertaste, not a fan but stores can't really keep it stocked. Curious to see how it continues to do or if it turns out to be a short lived fad.