1. If the fact is stored in the DBMS of the shop, use that. Do not create new configurational options for facts already covered by the data schema of the main shop. Otherwise, users will have trouble keeping both in sync. Also do not hard-code facts into the template markup unless you can be sure they are valid for each and every shop.
2. Aim for a quick and fast installation. Less is more in terms of options. Ideally, aim for a one-click installation process that just requires the minimal additional data and suggests notifying semantic indexing services (like GR-Notify).