by Jim » Tue Nov 20, 2012 2:38 pm
A theme is a combination of templates for pages, product, shopping cart, search, gift certificate, etc, images used on those templates, specific buttons used on the various screen, and colors used for various places on the site. Other, not so obvious settings, such as image alignment, font setting etc can also be set by the theme. So when you change a theme under Preferences > Themes, any or all of those things may change. Some themes have specific templates used just for that theme and some themes are designed to use the same templates as another theme but other settings of the theme make it look different.
When I first started with ShopSite back in 1998 all of the themes were based on templates created by C code. I think the custom template language was introduced in ShopSite version 5 or 6 and the C code templates have mostly been replaced by "custom template" versions that look and function similar to how the C did. Each release there have also been additional new themes added, all of which have been "custom template" language based. I think the only C (i.e. non "custom template") templates left in the product are a few product templates including Default_product_template, Graphic_over_text,Compact_product_template, Compact_graphic_over_text, Inline_product, Inline_graphic_over_text and One_line. All page templates are now "custom templates".
So your statement "I want to get away from custom templates altogether" doesn't make total sense, since it is no longer possible to have a ShopSite store without "custom templates". If you want to not use your own "custom templates" then all you need to do is select a theme under Preferences > Themes which will change all your settings to use the ShopSite provided templates (and other theme settings).
If you just want to change the templates from the ones you created to ones that ShopSite supplies, you would need to goto each location where a template is selected, Pages, Product, Search, Shopping cart, Gift certificates etc, and select a template that you like. The themes are designed to work together as a set so it may not be possible to just pick a page template and expect that any product template would work with it.