Welcome to the forum, these guys are very helpful.
If I can guess at your issues:
-You’re using Carbide Create and when you zoom in and out you’re having navigation issues. Have you updated to the latest version of Carbide Create (Version 303)? Navigation has been greatly improved recently. The ‘Reset View’ button also works wonders.
-Your design is cut out (or very nearly) and then moves around and catches the bit, ruining the finish. There are several solutions here; you can either use double sided tape to secure everything, use the onion skin technique, where the part is cut out save for the last 0.5mm or so, or use tabs (Unfortunately, Carbide Create does not support tabs yet). Check previous forum threads for more information on tabs.