Hi Tim,
You can do all that in a module. Basically, this module (let's call it MyModule) will manage a database table which contains the additional product data. You'll then provide a custom loop (say, MyModule\Loops\MyProduct class), that will extend the core Thelia Product loop (Thelia\Core\Template\Loop\Product), and return the additional data, by overriding the parseResults() method.
You'll the registrer this loop as the default Thelia Product loop in the <loops> section of the module's config.xml file :
<loops>
<loop class="MyModule\Loops\MyProduct" name="product"/>
</loops>
You're done ! Your product data are now available everywhere in the front-office template.
To manage you product data from the back-office, you can use the "product-edit" include hook, which will include the MyModule/AdminIncludes /product-edit.html file as a Smarty template in the product's "Modules" tab.
You can also create a specific page that will be displayed through the module's "Configure" button in the Modules section of the back-office. To do so, you can :
1) use the "module_configuration" hook: the AdminIncludes/module_configuration.html file will be included as a Smarty template
2) create your own template and controllers, and provide a route named "/admin/module/MyModule"
The "Colissimo" module is a good example of a T2 module, and demonstrates point 1)
The TheliaDebugBar module demonstrates point 2).
You can do A LOT more customization of Thelia data and behaviour in a module, specially manipulating events and events data. Be sure that a documentation about the fine art of writing T2 modules will pop up soon.
Hope it helps.
