General theme editing and setup questions

Hi all, I am new to OpenCart and trying to migrate an existing site built with Drupal to it.

I can accomplish everything I need by editing the 'Default Theme' files in the theme editor and a couple of paid extensions, but I am wondering if doing this way will cause issues later when I go to update the site or for the paid extensions to work properly?

What would the best way to do this be?

1. Clone the default template and make edits to this (will this affect upgrades and extensions?)
2. Just do it all on the Default Theme in Theme Editor (will these changes be overwritten when upgrading?)
3. Use VQMods - there are extensive edits to be made, seems like a lot of work.

Appreciate your thoughts.

when I go to update the site or for the paid extensions to work properly

If you upgrade any OC Version, possibly, existing VqMod/OcMod-Extensions may no longer function as planned. This, because such Extensions look for certain Code, to add/replace that Code with Custom Code. And if you change default Theme Sections, you better create a Custom Theme Name/Section, to place them there, to still have your default Theme Code within your standard Theme Sections. A Custom Theme may contain only a few Files, everything else will then be taken/used out of the default Theme.

And dont ever use the built in theme editor