Should I stick to the Swift track and Fun Facts course, or should I switch to the Swift 2.0 track beforehand?

You could go either way. The Swift 2.0 courses are still being developed, so it is not quite as complete as the older Swift courses. If you haven't already updated to Xcode 7, sticking with the older Swift courses would be fine. However, if you have upgraded your Xcode, then you could potentially run into problems trying to follow along with the older courses, as there will be changes in syntax between Swift 1 and 2. I have seen that, when they can, the instructors will add teacher notes to the older courses for those with newer versions of Xcode. But that isn't guaranteed to be the case for all courses.

Personally, I have kind of skipped through a few of the Swift 2.0 courses, especially the early ones, because there are very few significant changes. But I have gone back to the older courses to learn some of the more intermediate lessons. For example, Pasan's courses dealing with the Stormy weather app are fantastic, but they are currently only available in the Swift 1 courses. But that's fine, as long as you can deal with the changes in Swift 2 (or if you are still running Xcode 6).