The order of them is not important. So long as you are careful when moving them/editing that part of the code, it will be fine.
With this code you MUST have the forum set at the Default style or it can cause some quirky issues.
You can "try" it and see how it goes but you will probably have problems.
So you know this, Ive noticed that on some styles the tabs use the tabs from the default style. I have no idea why, nor how to correct that. (actually there may be some css edits you can do but its complicated to explain - mostly involves adding !important to each line of the css for those tab images so they don't use the other's)
There are dozens of other styles in the stylesheet board here so have fun adding them. Just be sure to only use those that don't require header or footer codes and you'll be fine.
ALL of the ones listed on my test site are also posted here. It is better to grab them from here however as they've been updated here and not necessarily updated there.