According to The Hollywood Reporter, John C. Reilly is joining the Ed Helms-led cast of “Cedar Rapids” from Fox Searchlight. Miguel Arteta is helming the ensemble road-trip comedy. Phil Johnston wrote the script. Alexander Payne, Jim Taylor and Jim Burke are producing via their Ad Hominem Enterprises banner. The story follows a wholesome and naive small-town Wisconsin man played by Helms who must represent his insurance company at the big-time and big-city regional conferance in Cedar Rapids, Iowa, after his role model dies. Reilly’s character, a family man, is also is attending the conference, but sees it as a vacation away from home who is taking the opportunity to cut…