startupraw

The plugin conflicts with cache plugins from time to time. Adjusting some of your caches can fix the conflict. If you use cache plugins. Deactivate the plugin and see if the woo commerce works. If it does then it is a cache plugin. if you do not use cache, then it is likely theme conflict. Could be bad coding on a word press theme that you are using as well. The woo commerce works with updated version for me. You can also try a commerce plugin called Easy digital downloads. It works well with conflicts. Hope this helps.
Startupraw

Changing your theme should not impact your ranking. Changing your page to a post could affect only what pertains to that page. I would leave the page, you are not going to see any difference in rank increase as a post.