Hello there CentralDesigns.
Regarding your question about the non-sequential order numbers. This is a question that often comes up in he tickets, so I'm glad someone has finally asked this in the forums so there is now a public answer.
Anyway, the plugin tracks carts as order numbers. So a new customer equals a new cart, whether they abandon the cart or complete it is besides the point, there will still be an order number for it.
So considering you see non-sequential order numbers, indicates to me that you're using one of the filters at the top of the "Checkout > Orders" section. The filter that allows you to view "Completed/Processed" orders only, see this screenshot http://screencast.com/t/E4XqcmeoHm1V
If you changed that filter to display all you will see the sequential order numbers but a lot of blank orders ($0.00) which are obviously all the carts that never make it past the billing step.
We have plans to track carts and orders separately to avoid any similar questions like this one.
I hope this helps answer your question.
Please contact via http://tribulant.com/support in future though for support related questions, the forums are intended for community discussions.
All the best!
Kyle.