Allegrato takes information from auctions and insertions systems and displays it on widget at frontend.
No, but some caching is highly recommended. Plugin dosn't have internal cache and without it will be pulling data from remote systems on every requests. It means that without some additional cache layer, site will work slow and will generate unnecessary trafic to remote system.
WP File Cache plugin. It is simplest solution.
WP File Cache stores data pulled from remote system into files.
Allegrato is able to use data from those files to display it on widgets so there is no need to pull data from remote system on every request.
Any other cache plugin that is able to cache widgets output would be good to.