That's cool, but what if I get to the new server and want to buy another slot for a character? Will I be able to? Someone stated a while ago that they were able to move all their 16 characters but were barred from making any new ones until they had gotten the numbers down to below 11. Deleting characters is not an option for me
You'll never be required to delete any characters to make a new one, unless you've maxed out the slots you have. The situation mentioned was a bug which I think Musco said was resolved. But if you buy an extra character slot now and log onto the destination, you should see 0/18 active characters.
But no matter what, you'll be able to fill out your purchased slots. CS would fix anything that went wrong anyway. Best of luck!