Any of these variables can be accessed in the templates using smarty template dot notation. e.g.:

{literal}{$config.company.contact_email}{/literal} will return: {$config.company.contact_email}
{literal}{$config.company.name}{/literal} will return: {$config.company.name}

And you can add as many custom fields as you wish and reference them anywhere your templates are parsed.
{foreach from=$configIDs item=conf} {cycle values=", "} {/foreach}
[{$conf.id|upper}]
{$conf.desc}