Hello, X-Carters
Please accept my apologies for the delay in answering to all your requests.
1. I can confidently state that 4.5.0 is a stable version and can be undoubtedly used for the live stores. As some of you have already mentioned there is no "bug free" software. It only depends on whether these bugs are minor or major. 4.5.0 version is as stable as 4.4.5. You don't have to wait for 4.5.1 and can unhesitatingly develop it.
2. UPS bug. We apologies for any possible inconvenience caused. Please try to apply DIFF_57313.patch attached to the following bugtracker ticket:
http://bugtracker.qtmsoft.com/view.php?id=41198
Patch application instructions can be found here:
http://help.x-cart.com/index.php?title=X-Cart:Applying_Patches
3. We are currently working on the database upgrade pack.
Thank you for all your feedbacks, suggestions and reports, we will take them into consideration.