Hi tony, welcome to Aeclectic!
There are many variations of the Celtic Cross out there -- probably every Tarot author who writes a book which includes it also modifies it in some way. Likewise, readers frequently make up their own spreads or modify existing spreads like the Celtic Cross. There isn't really any "one way" to do it. The version you have listed sounds perfectly fine to me. If you're interested in seeing some variations, you might do a search in the forums for "celtic cross" (the search button is at the top of the screen) and see what you come up with.
As for the positions of 5 and 6, I've seen them in different books listed both ways -- with 5 on the left and 6 on the right, and with 6 on the left and 5 on the right. So do whatever feels best!
There's another forum here called "Using Tarot Cards," which covers things like spreads, and this thread might fit better there. Perhaps one of the moderators of this forum will move it.