Ideally this data should be maintained in a database table accessible to WP. Then getting the data is a matter of making an SQL query. Coding the user interface is a sizable coding project though.
The data could also be managed as a custom post type with custom fields. Then WP will help you manage the user interface. This could be a challenging but doable plugin project if you want to get into coding more.
If you want something workable with minimal effort, establish the data as a PHP array declaration. While the format would be highly structured, once the structure is established, adding more data is fairly straight forward. You could maintain an array element template as a PHP comment from which you copy the structure into the main array, filling in the data as required.
Since sorting PHP arrays is easy and flexible, the order of the entries makes no difference, but the structure needs to be strictly adhered to. The data array could then be included on a custom page template that contains the loop that steps through the array and outputs the data after it is sorted.
There’s all sorts of loop schemes to manage left/right output. For example, maintain a loop counter and output left or right HTML based on the counter value modulo 2 result. Or output everything as an unordered HTML list (the data is ordered, not the HTML) and use jQuery’s Masonry to parse everything into a pleasant structure.